Re: thinkin about the v8
Because you are going to be building up an old CJ your main problem is going to be space to fit all the hardware. The Spicer 18 x-case that you have in the jeep now is really your only choice. I put a Chev 350 into a a CJ 2A once with the stock T90 tranny and Spicer 18 x-case behind. The only problem I had with this set up was that I blew out the tranny and the differentials from the power of the V8.
I suggest that you decide what motor that you want to put in the jeep first (ie 4,6,or 8) then pick what brand (AMC, Chev or Ford). Once you have decided what motor you want, select a tranny that is a direct mate with the motor and bell housing of that motor. This will save you a bunch of money for adapters and work. There are several to choose from for Ford, Chevy or AMC. Try going to the <A HREF=off-road.com>off-road.com<A/> tech pages and do a search of motor, tranny, and x-case combos.