Aw, if you want to go Nissan, go whole hog and swap in a RB26DETT (2.6l twin turbo). It was the standard engine in the Skyline. Comes standard with a 5 speed transmission and all wheel drive! About 300 HP stright from Nissan. Problem is a front clip usually sells here in the US for over $3,000. I guess the intercooler might look out of place on a Jeep though. Back to your original engine choice, would it be possible to use the Nissan tranny and either adapt a transfer case or even use the Nissan case?