for the v6 id say go with a gm 3.4, 4.3 or a buick 3.8. the buick can be wobbly though
if you felt like more of a project, you could pick up a toyota 7MGE out of a '86-88 supra and cram it in there(it's a straight 6). those things pump out 300hp easily
i'd have to say go with a toyota transfer case. ott industries makes an adaptor so you can run it devorced from the tranny.
http://www.ottindustries.com/divorcetoyota.htm
a breakdown of parts costs that i'd imagine:
toyota front axle: $200
toyota rear axle: $150
toyota t-case: $100
t-case adaptor: $300
engine: $1000(rough estimate)