alot of your general car purchase questions apply, obviously they become more critical with age of vehicle. A lot more is in the inspection as the seller may not know the answer or be less inclined to convey the knowledge if it may hurt the sale. Its easy to play dumb as well as be overly proud of you pile of ****. Ive experienced both
Maintenance/repairs that they have done or had done under ownership
Maintenance/repairs done under previous ownership
how long have they had it ? how many miles did they add? how did they use it
current issues or things that dont work, or work just right
test the turn signals and wipers and headlights, and maybe even at same time
dont bother asking about rust in person but get in there and look, take a magnet, dont get fooled by shiny paint or worse diamond plate.
Solid drivetrain and little rust as possible is where to start...... but you already know this

then use the little fixables for bartering
Did you ever call Kevin in fuquay varina with the red one? or any reason you dont like?
For your search in general...
Spend time in the 40 section. Read, read and read some more and educate yourself on what you want and what years had what to offer. Ask yourself some ?s are your really gonna work on it or have the $, do you really want factory equipment or are modern mods like GM powersteering seats motors ok by you. Check out quality of swap as in is it a mess of wires, nice and tidy, clean/oily?, check in the overflow bottle and look under the radiator cap to see if oily or milky. If nothing else you will know more than the owner or at least have him thinking so which will fair well in you offer. good luck