The GM 60 deg V6 (in any of its RWD iterations - 2.8, 3.1, 3.4) fits a Gen I Troop just fine.

Or, find a later-model Isuzu-built V6 drivetrain such as was done by Chad Hunter; here's info from a Very Very old post by Chad:

"I have a '94 3.2 in my '87 trooper. I used the '94 tranny as well. The crossmember is in the same place on both trucks. I cut off the rodeo's motor mounts and welded
them in my trooper. The motor fits great and it looks factory. The only trouble is that the e-brake won't work with the v6, I'm still working on that one. If you can
find a good donor vehicle I think that this swap is a good option"

You'd have to go EFI on this swap though, since the later Isuzu-built 3.2's and 3.5's are MPFI. IMHO the GM-V6 swap would be tons easier since you can do it carb'd.

It'd be far far easier to start off with a donor Isuzu V6 rig than it would be to adapt something else like S-10 drivetrain but anything can be done with much determination I reckon!