I just completed the same swap. I have a 90ish mj now. The wiring in the cab will be fine. You just have to swap the engine harness. That does include the brain. I went from a 2wd, 2.5, 4 speed to a 4wd, 4.0, auto with a 242 t case and every thing bolted in. I had a 89 donor xj. Just watch everything you take apart and it is not bad. On my donor I labeled all six injectors on the wiring side because I have heard to many nightmares about getting them staight. Every Question I had was covered in a forum somewhere so it should be no problem. Good luck and if I can help let me know.