I'm currently swapping my 94 2.5 over to a 95 4.0. So far, I've got $450 invested in the motor, trans, tc, wiring harness, rear driveshaft.
I just ordered new frame side motor mounts for $95...and I'm not really sure what else I'll be needing at the moment. For simplicity, I went with an ax15 so I wouldn't have to be concerned with wiring the aw4 controller.
I could have likely had it done in 3 solid days if I wasn't waiting on the mounts. Everything else went sooooo smooth until that.
1994 Wrangler...4.0 AW4 swapped, sye'd, 5.5" lift and 33's
I would look for an XJ Cherokee (the cherokee sport) in a junkyard. Get the whole motor, transmission, and transfer case. Probably also the wiring and ECU. Its almost identical to what they put in the 4.0 Wrangles anyway. But like highgrad says, the only new parts you *really* need is a new pair of engine mounts, because you'll have to cut the 2.5 mounts off the frame.
i swapped my 2.5 to a 4.0. it was a 90 originally, and i have all of the wiring harness out of a 94 and my engine, transfer case and transmission are out of the 96 cherokee sport. i cut and rewelded moter mounts and trany mounts, and almost everything else went into place. i also snagged a set of 93 guages and those all bolted up and wired up as well. i still have the 4.10s out of the 90 so i have plenty of power!