Laine,
If it was me and the frame, suspension, and cab was bent up, know I am not emotionally invested in my truck, I would look for a really nice IDI that is straight and clean and build off that. (Upgrade.) Run it like it is if nice or if my truck had say a better engine, radiator, rear axle, and such swap that out. Faster, easier, and potentially not much more expensive. Your time is worth money, parts are not cheap, and it takes lots of tools. Add up the cost of a frame, cab, suspension parts, new parts, wiring, paint, tools, and your countless hours of time you are likely to spend more than buying one. There is a old saying in the restoration business. How do you make a old classic IDI worth 10k, put 20k in it!
If I could not find a really nice IDI after say 6-12 months of looking I would look for a really nice gasser and build off that. Maybe in your case frame up so you can paint he axles, frame, driveshaft, etc. Move your wiring and dash over too so it is set up like a IDI was new.
As some have mentioned maybe your truck is not as twisted as you think. Maybe someone can fix the frame and you can fix the suspension. (A picture says 1,000 words so post some of the damaged areas for us to ponder.). And it will be good enough for government work as they say. But if the cab is now twisted, the firewall is really bent, you will have a hard time making it all straight. Harder yet putting what you have on a straight new frame. For instance if the cab is bent it will not line up perhaps evenly with the fenders or bed. Now a guy who works a frame/body rack every week for the last 5 years can potentially can make yours 95% straight, you and I are not that guy.
Send some pics so we all know more about the damage. Maybe it is not as bad as you think. Maybe it is. Keep in mind we are not as invested as you, maybe you want to go a different direction and that is fine too. Your truck, your life, and your future.