First, although I never did a swap, I did a little research when I wanted to put a 5.0 & AOD transmission in my 93 Explorer. In fact, I was "this close" to buying a BII with a TBI 5.0, but I ended up getting a full size Bronco instead.
There are a few places on the net that sell conversion kits. I know of two places off the top of my head,
Advance Adapters and
Kaufmann Products. If you would like, I could dig in to my saved web pages to see if I can find any more.
In fact, I ordered a "Bronco II and Ranger V8 Engine and Transmission Conversion Kits Instruction Manual" from Advance Adapters when I was going to do my swap.
As far as 4WD is concerned, as long as you get a transmission made for a 4x4 vehicle, probably the only thing you will have to worry about is the driveshaft. By that I mean you may have to modify it (shorten it) or replace it.
