Pull up the carpet and check the floors for rust. Also the wheel wells.
Then turn on the blower and make sure the fan works (not the a/c fan, the heater/defrost fan) and doesn't make any noises like its dying. They're supposed to be a huge pain to replace.
Look at where the steering box bolts to the frame/body in the engine bay and also behind the front drivers tire. If the mount is broken, it can be fixed by welding in some plate, but if you don't weld that can be a kind of pricey fix. My $2500 car gained $1000 in "value" after I had that repaired
Look at the front and rear windshield seals, if they're cracked and dry, water will leak through. I replaced my front glass, but I can't find any place that sells rear glass for this car, so you should probably check for cracks in the rear glass too
I don't think there's a whole lot else that's specific to this body. Same mechanical checks to the engine. The IP has its own lubricating oil, so you could ask if its been changed. And the air filter is an oil bath filter. You could check or ask about the frequency of that oil change/filter cleaning.
Glow plugs aren't that big of a deal. I swapped mine for the pencil type and it helped in the winter, but summer time, its hardly a noticeable difference.
good luck!