i have lifted a few xj's & i found that most will take up to a 4" lift before you have to mess alot with the driveshafts. if you go above 3" to 3.5" then you will end up lowering the t-case, extending the brake lines front & rear, changing the lower control arms & trac bar & front disconnects. & you will want to regear after 32" tires.
i am with you DBL...i have a 92 with a procomp 3.5 & a set of hercules mt's 31" & a winch & i am so haaaaapppppppyyyyyyyyyy!!!!!!!!!!!
a ful kit is the best way to go one that has the t-case drop, the trac bar relocation brackets & the brake lines & the springs & shocks & a steering stabalizer. try to get spring packs for the rear if you can afford them. add a leafs arent too bad but they go out after a couple of years.