The title says it all?
Is it possible or not?
Just drop it in and get it running??

 

I am not an expert, but as this post has gone unanswered I will try, at the very least it will give your thread a bump and more experienced posters will correct me.
I would say not easily (not plus-N-play if you will). Without looking directly at your 88, I suspect it could be done at some level, but depending on specifics it could involve changes in wiring harnesses, computer, perhaps even motor mounts (the 86XJ I used to own had different motor mounts than the 96 I own). I had a 88 for a while but can't remember the specifics. I know I looked at doing the exact same, dropping a mid 90's 4.0 into the 88 and decided it was beyond my level. In general I would say if you drop a fuel injected 4.0 in place of the carbed 4.2 you have to have some method of electronically controlling the 4.0.

FWIW...

 

I know for sure that their is a difference between the 94's and the 95's. They started to change sensors, but in 88 it may have been one of the beginning years for that generation of the 4.0. So it may work