the body on that truck looks pretty decent for over 25 years old. frame doesnt look too bad. But I would look at it this way:
that truck is just a rolling chassis. Unless the guy starts it up and it moves under its own power, that is what I would treat it as.
2 years sitting in the weeds with the windows down will pretty much make sure your electrical switches and whatnot are going to be flaky at best due to dirt and corroded contacts from being open to the elements. Then you have the rodents to look at. they have probably chewed a boatload of wiring under the dash and in the engine compartment.
the power steering pump is shot. (no cap, all sorts of bugs moisture in there, I would not even attempt to use that, as you wil probably trash the rack seals if you do, provided they are still good)
it is a 2.8, and it is probably not worth the expense of buying the seals and whatnot to fix any leaks if the seals are shot (likely, after two years of sitting)
also any rubber in the engine compartment is probably bad as well. (hoses, belts etc)
Interior will have to be ripped out from carpet to headliner (of course you knew that)
If your other ranger is good for a motor/tranny and interior swap into this one, you are doing good. I would offer him 200 bucks. if nothing else, he might come down to 300 or 275. doesn't hurt to ask.
just my thoughts
AJ