The 2.5 is not a v6
It's the wimpy little chevy 2.8 v6 that was an option in the late 80s XJ's. Easiest swap would probably be a 350 v8 for plenty of power. You will for sure need motor mounts, a new tranny, and probably a bunch of other stuff, but you should be able to use Advanced Adaptors for the tcase etc, though they won't be cheap. Check out the Cherokee forum at
www.jeepsunlimited.com the guys over there are very knowledgeable and will probably be your best bet.