The wiring issues (poor quality insulation) is something to be concerned about. The general consensus is that '88 is the first year for the better insulation. Look at the big plastic junction plugs at the firewall behind the intake manifold. The condition of the plug and wiring at that point as well as by the alternator are good indicators of what the rest of the harness is like. 89 is the first year for 2.4 injection and the OEM ECUs have an inherent problem. If the ECU (behind the right kick panel) has been upgraded to a 9 series you are good. 89 is also the first year for the flywheel ignition trigger/sensor. It snakes down behind the valve cover/head from the wiring harness. Though not always visible, if the pigtail is visibly damaged, you'll want to see to it BEFORE you drive a long way. For the earlier cars (pre 86) I like the 85 as it is the first year for the B230 engine (lighter construction). That said, many people swear that only the earlier cars with the heavier B23 engines are worthy. Prior to 83 you'll have K-Jet, a mechanical injection system. 90 and up you get a driver's airbag. 92 and up (and on 91 SE models) you will get ABS. Prior to 87 the manual cars are M46--four speed with electrically activated overdrive. 87 up manuals are true 5 speeds. The M47 has a tendency to be a little noisy unless it has been overfilled with oil to help lube the 5th gear which is high in the gearbox. 93 is the only year that came from the factory with R134. My experience is that all of the cars respond reasonably well to a conversion, but none of them cool like Frigidaire in a Delta 98! Watch for center drive shaft bearings binding. They start out by making a very quiet hissing sound and when they get really bad they bind and thump, whump, grumble and grind--taking the driveshaft on a trip while they do so. Watch for corrosion in door openings, around wagon rear hatch windows and on wagons pre-86, around the side windows. Fender arches out back too, in very damp areas. Clunking suspension is bushings. Fronts and torque rod bushings are easy--the big ones in the middle of the trailing arms not so easy. Listen to the blower fan. If it makes noise at any speed, it's on it's way to the trash heap. Transmissions will last 250k if they have been serviced regularly right from the start. My opinion is that if the first service wasn't done until 75k, a huge piece of the gearboxes life was lost. Of course it's often impossible to know the history in most cases, but your concern is justified.

Good luck!
DS