First off, Welcome! :cheers:
It's hard to say without knowing the year of your truck. There really isn't much in common between a Renix era (86-90) 2.5, and a 94 4.0.
Why are you ditching the XJ? If it's because of rust or body damage, you might consider yanking the entire drivetrain, cooling system, and wiring to swap into the MJ. You'll have everything you need, except for a rear driveshaft.
A front skid and T-case skid will be a direct swap onto the MJ.
Looking forward to seeing some pics of the truck!