late 86s got the 4.0 firewall. but even yours was different, a couple whacks with a big hammer will make the small change needed.
the bigger issue is the hood and hood latches that changed to fit the longer engine.
If I can get my butt to the yard (dad's in the hospital again), a KJ renegade just showed up at one of the pullaparts and I'll try and remember to snag the knobs too.