Concur. For simplicity's sake (not making extensive mods to the front clip,) you should consider
A) Cranking up the AMC 4cyl already in there - it's really not a bad engine (for a four cylinder...)
B) Putting in a GM V6-60. NOT the 2.8 that it might have come with - a 3.1 or 3.4 from an F-body or an S-10 is the ticket here. DO NOT use the FWD version - the starter is on the wrong side, and won't work with RWD/4WD transmissions!
C) Check out Advance Adapters, and look into the SBChevvy mount kit. They make it a largely "drop-in" swap, and if you don't have emissions regs to wrestle, with, you can drop in an engine that will run on its own, and just needs power to the coil and the starter to run. If that is a problem for you, there are also a few engine control systems out there that are truly standalone (Accel, MSD, and Painless Performance all come to mind for some reason) that will let you make sure everything runs on a stand, then drop the ENTIRE SYSTEM into a chassis.
Just some thoughts. Bear in mind that the front clip was redesigned in 1987 to fit the longer 4.0 I6 block - I think something like 8-10" was added, and that's not just something to be knocked up in your backyard...
5-90