some friends of mine with too much time & energy & way too much imagination built a 383 six pack in a 94 xj & that went over like a lead balloon! twisted all sorts of stuff even after they did alot of welding LOL . then the guru's built a cummins turbo diesel xj out of a 2000. that one worked ok for about 2 months until they hooked up a bully dog kit to it. the time money & energy spent is enough to make you say WOW!
you can build & buy 4.0's that will rock a mustang.

i have a 93 4 door xj with a 3 inch custom lift & a 4.6 stroker that i had built. i can run 5.0 stock stangs for 1/8 of a mile before they get me. but they cant touch me in the woods!!!!