The Lower Intake Manifold gasket is frequently a problem, because people don't change out the antifreeze periodically like they are supposed to, and it turns acidic and eats the plastic gaskets. Replace with aluminum gaskets, and flush out the cooling system. You might also take this opportunity to convert to Ethylene Glycol antifreeze instead of Dexcool, but be sure your flush is thorough because the two don't play well together (unless you go to "universal").
When I obtain an older car, I like to power wash everything so leaks show up. Valvecover gaskets can sometimes be an issue.
Rust around the rocker panels can be kinda nasty. So can rust around the strut towers (esp. rear).
It's quite possible the plugs and wires are still factory original. Especially if you see the cylinder #'s on the spark plug wires (replacements don't have the cylinder #'s printed on the wires). If you go after the lower IM gasket, it would be a good time to do this (and clean the throttle body like Bill suggested).
When I pick up a GP, I like to throw in Monroe Quick struts and Raybestos Brakes on all four corners. Just a personal preference there.
Transmission fluid might have never been changed. Many people like to add a shift kit.
Supercharger coupling can be an issue. Some shops will tell you to replace the whole supercharger for $1300 but you really just need the plastic coupling. And BTW you might want to change out the supercharger oil, good chance it's never been touched. The old stuff has to be sucked out.
