Becky,
You have been so gracious and patient as we talk through possible options for your son. It helps me so much to gain a clearer picture before advising something too quickly that in the end would not truly be a good fit (simply because I didn't have enough facts to advise you well). So, I appreciate the time you've spent sharing about your son.
I agree with you that learning to read and follow lengthy written directions independently is a life skill, and when the skill is new the reading level and tasks being assigned need to be easier so the real skill of following written directions can be developed. So, the science directions that your son is learning to read and follow well in CTC are doing exactly what we desire them to do, which is training your son in this important skill!

This will help him so much next year and in the years to come.
In pondering the amount of writing and reading your son is currently doing, and keeping in mind the myriad of skills called upon daily in the various guides, I am leaning toward your son doing Revival to Revolution as his best overall placement. This is because there will be enough new skills there to stretch him, but we don't want to overwhelm him either. The primary source documents, historical poetry, and quantity of mapping definitely raises the level of this guide, along with numerous other skills that will be great to practice.
I would have him do the Extension Package for sure (which is scheduled in the Appendix by day). It would also be excellent practice in following written directions for him to complete the History Projects. It would be up to you whether or not to complete the 50 state study. The Storytime books can be optional at his level, as long as he does the Extension Package books.
I would also recommend doing the advanced version of the Exploration Education science, along with the inventor study for science. The Advanced Version earns high school level physical science credit with lab and is scheduled in the Rev2Rev guide.
For English, I would be inclined to do Rod and Staff English 6 at half-speed as scheduled in Rev2Rev (with the other half to follow the next year in Missions to Modern Marvels). Be sure to do most of the lesson orally or on a marker board with him, assigning just one part to be done on paper on his own. Rod and Staff will get to those outlining, report writing, summarizing skills as you progress through the levels. So, even if the diagramming is a review, the writing instruction will be excellent for him to have.
I would also lean toward having him do Level 6/7/8 of Drawn into the Heart of Reading with the Level 7/8 Book Pack as scheduled 3 times weekly in the Rev2Rev guide for literature study. Link:
http://www.heartofdakota.com/drawn-into-optional7-8.php This will help him get some formal literature study under his belt and will be something you can help him with to be sure he is successful.
For writing, while I dearly love the Exciting World of Creative Writing within Rev2Rev, I am thinking some essay writing coursework would be good at this juncture. So, I would be inclined to have your son do Essentials in Writing 10 from the World Geography Guide, doing two lessons each week throughout the year. You could just order the Essentials in Writing 10 and do it without the World Geography Guide's plans as the lessons are quite straight-forward. You would do this in place of the Exciting World of Creative Writing. Link:
http://www.heartofdakota.com/hearts-for ... #writing10
If desired, you could stick with the Hebrews study and the Who Is God? study as scheduled in Rev2Rev. You could add additional quiet time Bible reading to round out the hours needed for 1/2 credit of Bible. If you felt these studies were too easy, you could devise your own Bible plan instead for credit.
The Music Appreciation is an area that you can also decide whether you desire to earn credit. Most colleges want to see one credit of Fine Arts credit on the transcript. You could earn 1/2 of this credit by having your son complete the Music Appreciation study in Rev2Rev (and just listening to additional classical music to round out the 1/2 credit). Then, the following year in Missions to Modern Marvels, your son could do the nature journaling assigned with additional drawing to earn the other 1/2 credit of fine arts. If you felt your son would eventually reach and complete the High School World History guide, then the Fine Arts credit could be earned there as scheduled in that guide instead.
With these thoughts in mind, your son would earn the following credits with Rev2Rev (doing it as written with the exception of the Storytime and possibly replacing the Bible with a harder option if desired):
1 credit American History in the context of World History (mid 1700s-1900s)
1 credit English (includes Drawn into the Heart of Reading for literature/grammar 6/Essentials in Writing 10)
1 credit Physical Science with Lab (using EE Advanced Version)
1 credit math (of your choice)
1/2 credit Fine Arts: Music Appreciation
1/2 credit Bible (either with supplementation of what is in Rev2Rev or a different method of your own choosing)
Consider adding: 1/2 credit Spanish I (Getting Started with Spanish)
Consdier adding: 1/2 credit Government (see suggestions below)
You could also choose whether to add "Getting Started with Spanish" for 1/2 credit of Foreign Language, doing a lesson a day all year. Link (scroll down to see Getting Started with Spanish):
http://www.heartofdakota.com/hearts-for ... ckages.php
Then, the following year, your son would progress into MTMM. For English, he would do the last half of Drawn into the Heart of Reading 6/7/8, Write with the Best II, and the last half of English 6... all as scheduled within MTMM. He could do the Bible study as scheduled in the guide for 1/2 credit of Bible, as it is high school credit-worthy. He could either beef up the Chemistry study in MTMM with our suggestions, or do the Chemistry from the new American History high school guide which will be out next year. The nature journaling could be used as an additional 1/2 credit of fine arts if desired.
The last year of high school, he could either do World Geography or World History, depending on which suited his needs better. I would be inclined to do World Geography (but if he needs credit in World History which you feel cannot be covered by his trip through Rev2Rev and MTMM, he could do World History instead.)
If your son needs credit in government, we can help him earn that credit as well. The beginnings of government is in the Rev2Rev guide. So, he could earn 1/2 credit in government by adding to what is already there. In the area of government, you'd already be studying the signers of the Declaration of Independence through Rev. to Rev. and reading the Declaration of Independence. Plus, the history readings already in Rev. to Rev. would discuss government concepts too. So, to finish out the government credit, it would make sense to add something like The 5,000 Year Leap for government and alternate reading a chapter of that with reading some of the The Federalist Papers. If your child also read the Constitution, this would all add up to a semester of government credit (.5), when used in conjunction with what you're already covering within Rev. to Rev. Listing the Declaration of Independence, the Constitution, some of the Federalist Papers, the research on the Lives of the Signers, and the 5,000 Year Leap, you would have a strong high school government course. Another thought for government would be to instead add Zeezok Publishing's A Noble Experiment. This could likey be done just 2-3 times weekly or done on your free 5th day (doing two lessons) to give you the 1/2 government credit needed.
If your son needs credit in economics, we can help him with that too. The beginnings of economics is in the MTMM guide, so he could earn a 1/2 credit in economics by adding to what is already there when he does MTMM. We'd be glad to help you with this.
Anyway, I know this is a lot of information, but in all honesty we just need to focus on the high school years one year at a time. I think Rev2Rev as close to the way it is written as possible is a good choice. Let me know your thoughts!
Blessings,
Carrie