Converting from 4 Spd to Auto. Questions?

[Erl]

Interested in the pros and cons of different automatic transmissions and transfer cases for my 68 3/4 4x4. I will purchase them as a unit to make things easier. Would the easiest swap be a T350 trans and trans case asm from a 70-72 1/2 ton. Then the front drive shaft is the same and the trans case shifter and linkage will bolt in. Plus no electronics, only vacuum and a kick down. Not so easy to find and no overdrive. How about a 73-86 series T350 or T400 with a NP205. Will the original front drive shaft still work? Any clearance problems, other than moving the cross member? Are electronics required? Or a 700R4 with a NP208. The overdrive would be great, but how hard is it to control. Just looking for some input before starting to procure the parts.