Okay. Some updated thinking. As I'm researching more and more, it seems my idea to use the 60-62 2wd chassis and convert it will basically be impossible with the giant X brace in there. I would need to at least start with a ladder style frame of the same wheelbase from 63-66 if I'm going to convert, but ideally a 60-66 K type 4wd chassis. OR do the 73-87 chassis swap, but it seems like that would have some "body lift" to it because of how the frame kicks. Or???? Am I thinking about this correctly? Are 60-66 K10 style 4wd frames pretty available if I need to do a frame swap? And if I used a K10 frame can I use the 73-87 springs, or do I need to use the earlier springs?
Also. On the transmission situation, it seems the best option might be to have a high end heavy duty 700r4 built that I know I can depend on. A little spendy, but I think I'll get what I pay for in that case, if I go with a 700r4. Maybe something like this PerformaBuilt Heavy Hauler:
https://www.performabuilt.com/produc...-hauler-700r4/. Then adapt the NP205.