I went with the 200-4R for mine. No driveshaft work to install it, the holes are in the correct place to slide the crossmember back, and the local transmission builder said they are better than the 700R4 in many ways.
Found an article supporting it, though it's a few years old.
http://www.carcraft.com/techarticles...mission_build/
I've had the rebuilt/upgraded 200 in my truck for a year now with the 350, and no troubles at all. Everything I have read says it will handle the 402 big I'm going to install next month with ease.