In thinking through what has been shared thus far in the thread, and in looking at your state requirements, I see a couple of options that you could consider. As you're weighing your options, it is good to think how much tweaking or adjusting you'd be doing to each guide. In my mind, the least amount of tweaking is a good thing (as it is just easier for the student to know what to do each day).
First of all, I'm thinking that doing Rev2Rev and MTMM and adjusting in the areas as needed would work for your son's final two years of high school. So that is definitely an option. In that option, you would be tweaking the science and literature and Bible (or even replacing it in some cases). This can be done, it just means that you'll be on your own a bit in those areas.

You'd also have some extra things that are typically required that you may have to add.
Next, with this in mind, it is worth talking about potentially using the World History guide for your son's junior year to see if that results in less tweaking. So, as I think aloud about this option... your son could do the literature from the World History guide with no tweaking. He could also do the writing that will scheduled in that guide as written. Then, you could continue with the grammar you've already been using. This combination would give him the needed full-credit in Literature (and when combined with what he did in the World Geography Guide could count toward a semester up to a full year of British Literature if that is a requirement for your state, which it usually is). He could also do the ACE Biology with Lab as scheduled in the World History guide that he still needs as part of of his required sciences. He could do the Bible as written in the World History guide and earn a full credit in Bible (this would include doing the Pilgrim's Progress study in the guide). Your son would also have a semester of Total Health that he could do as scheduled in the World History guide (which is probably also a requirement as part of your state's health/p.e. goals). If he needed a 1/2 credit up to a full credit of Fine Arts, he could also do that from the World History guide. Last, if he did the Spanish in the World Geography Guide, he could choose to continue with the Foreign Language option that will be in the World History guide. These would all be credits that he could use from the World History Guide "as is" each day (before we even look at the History portion). It looks like this in list form for your son's junior year transcript (leaving history off for the moment):
Literature/Composition/Grammar (English: 1 full credit)
Biology with Lab (Science: 1 full-credit with Lab)
Bible: Old Testament Survey (1 full-credit)
Health (1/2 credit)
Fine Arts (1 full-credit)
Foreign Language (1/2 credit)
Math (1 full-credit)
Now, as we look at the history, while your state requires either World Geography or World History it is obvious that you don't have to have world history due to your son covering geography twice. One of the Geographies he has done will be listed as an elective at this point already (which is fine, because your state didn't specify a 4 year plan for history). I would probably list the BJU Geography as Cultural Geography on your transcript. Then, you could list World Geography for the HOD course. One will be an elective and the other one will be a main course. Either one can be listed either place.
Next, as we look at World History (while it is true that you don't need it for your state's requirement for graduation, it is also true that you don't need the history that is listed in Rev2Rev for your state's requirement for graduation either). So, you are comparing two histories that are not required. Either one could be listed on your transcript as a history course and wouldn't need to be shifted to be listed as an elective. This is because many colleges do want to see the traditional history courses of World Geography, World History, and American History on a transcript. So,it is fine to list the course without making it an elective. Just because a state doesn't require it for graduation, doesn't mean that a college won't want to see it listed. College entrance requirements trump high school graduation requirements. So, if your son is looking at community college, I would find out what their entrance requirements are.
With this in mind, taking World History is a good idea, as it is a regularly listed required course in many states and for many colleges. This means that doing the World History portion of the World History guide would be of benefit to your son and look good on his transcript. So, you could do the World History part of the new guide too. This would add a full-credit of World History. At that point you'd need to add math to be done with his requirements, and you could use everything in the World History guide.
If you did go that route, I would also add a semester course in Economics to your son's program. I would do it on his free 5th day each week, so as not to add to the rest of his load in the World History guide. It wouldn't be so hard to do Notgrass' Economics that way. You could have 35 longer sessions on your son's free 5th day, doing 2 day's work on that free 5th day. Or, he could do one session each week all year on the free 5th day, and then finish the other half of the course over the summer. You could downsize a bit with Notgrass Economics, as your son would be getting some Economics eventually in his American History course too. Or, maybe your son would rather do Notgrass Economics over the summer entirely, as his only course, working at his own pace. This would allow him to leave his 5th day free all year long instead. Either option would work.
So, if you did the World History Guide, and added Economics you would also add in addition to what we've already listed above to your son's junior year transcript:
World History (1 full-credit)
Economics (1/2 credit through Notgrass)
Total junior year credits: 7 1/2 credits (with only the Notgrass Economics having to be done over the summer or on the free 5th day - no additional planning or tweaking on anything else)
Now, we come to the pondering of what you would do for his senior year, if you do happen to go the World History guide route for next year. In looking at your son's senior year, you would need American History. One source you shared specified 1877 to Present. The other source did not. In going with the more specific source, MTMM would fit that requirement. So, you could potentially use the history from MTMM, including the beginnings of the Economics study in that guide to list as part of your Notgrass' Economics if desired. Beyond that you could look to the new American History guide that we will be coming out with to fulfill your other needed credits.
So, you could use the American Literature and composition as planned in the new American History guide for one-full credit there. You could use the Government as planned in the new American History Guide for 1/2 credit there. You could use either the Chemistry beefed up in MTMM or use the Chemistry as planned in the new American History Guide. Either would work, but the Chemistry in the new American History Guide would be stronger. You could continue on with the Foreign Language coursework in the new American History guide (if you did it as scheduled in the World History guide), giving you 1/2 credit there. You could use either the Bible in MTMM (for 1/2 credit of Bible) or use the Bible as scheduled in the new American History Guide (which will be one-full credit of New Testament Survey).
The credits would look like this:
American literature/composition/grammar (English: 1 full credit)
Chemistry with Lab (Science: 1 full credit with lab)
Bible: New Testament Survey (Bible: 1 full credit)
Government (1/2 credit)
Foreign Language (1/2 credit)
American History: 1877 to Present (History: 1 full credit from MTMM)
Math (1 full credit)
It is also likely that we will include Speech in the new American History guide, which would give you that 1/2 credit there to add to your list above. That brings your credits to
6 1/2 credits for his senior year. To teach that year, your son would do the left page of MTMM each day and the right page of the new American History guide for all the rest, plus the government and foreign language boxes from the left page of the new American History guide. In essence, you'd be replacing the history from the high school guide with the history from the MTMM guide to get what you need. Beyond the using two guides, there would be no tweaking. Your son would do what was written in the guides each day.
I share this not to overwhelm you, but to help you explore options that would lead to less tweaking. Had your son been coming up from RTR into Rev2Rev this coming year, I wouldn't have shared all of this. But with the fact that your son is successfully completing the World Geography Guide with few to no changes (outside of grammar), it would be of great benefit to both your son (and to you) to go forward as much as possible with all academic areas.

Honestly, it is complicated to explain but easy to do.
In summarizing, your son would do the World History guide as written and add Economics for his junior year. For his senior year, he would do the history from MTMM and the new American history guide for everything else. See! It really is simple!
As you ponder, let me know if you have questions. I'll just say in closing, that I am very thankful for the gracious ladies on this board that do much to help one another talk through possibilities. Without all of you, there would be no HOD Discussion Board! Thank you for all you do to guide and uplift one another on this homeschool journey!

I am grateful for the board every day.
Blessings,
Carrie