If he's asking that much for it, it must have average or less miles for the age and be in good condition. I bought a '91 2 years ago for a little more than that. Shifted good, motor was tight, and it stopped straight, no body work needed. Still has the same sparkplugs as when I bought it.
If the clutch doesn't slip when you shift from 1st up to 3rd (skip 2nd) at a slow speed (about 15), its probably OK. K member don't know, never done one. Pedal should be moderately stiff. What you do want to check for is the plastic part under the dash where the cable plugs in. That part of the clutch is weak and prone to breaking under hard use. The 5.0s have 8.8" rear with TracLoc. They will wear over time and see the left side give up on traction. For that price, everything should work, windows, locks, wipers, radio, and all be there, no body work. Put it on the lift and look under the car. Get the vin and put it into the free carfax checker.
Tires should be good, check tie rods and make sure no play at the ends or at the rack. Mufflers your choice as almost everyone changes them but check for leaks. Brakes, should be firm, no spongy pedal. Check fluid levels before you crank the car, and when I do that, I usually take a general notice of if its clean under the hood, oil in any bad places like on top of the manifold, on the headers, down the back of the motor etc. then look for blue smoke when it starts up. Blue smoke means $$ in rebuild, black smoke means a tune up or emmissions stuff. It should start, run and idle right off without trouble. Some mods can add value like a short shifter, headers, subframe connectors. Detractors would be ripped out rear subframes where the axle arms bolt in (that's why I'd put it on the rack), body work, broken glass, needs top on a Vert., wheels been curbed (usually sign of female driver). That'll give you plenty to go run with. L8tr, Ron