Will have too completely disassemble the 700r4 and install a 4x4 out put shaft. an NP208 from a turbo 350 will bolt right up to the 700r4 and will be able to use your current drive shafts, or an NP241 from a k-5 blazer 1989-91 will also work just the same, the NP241 is a little beefer than the NP208. If you want a NP205 you will need to find one from off the back of a turbo 350, usually 1973-79 were the only years they offered the np205 behind the turbo 350. You will then need a 2 inch spacer to go between the np205 adapter and transmission, I have a company that I use for this part, if you want it pm me. will also need too change the rear drive shaft to a slip instead of a yoke slip joint. Also the trans cross-member will need to be moved back 2 inch's.
So if you use a NP208 or NP241 from off a turbo 350 everything will bolt right back together no changes necessary, if you use the NP205 read above. I'm doing the NP205 -700r4 conversion for a friend's cucv right now will post pics soon.