I'm a novice myself, but I've been looking for a 78 SA for a little while. I haven't found "the one" yet, but let me play devil's advocate and throw out a couple points for you to think about.
1. Assume it is at best a #3 daily driver until proven otherwise. A car always seems to look best at first glance, but upon further inspection more flaws keep popping out. The paint description alone takes it out of my #1 definition. Plus, if you haven't had a good look underneath at the frame and suspension, assume the worst rather than the best.
2. The oil on the inside of the tire sounds like a brake rebuild to me. Not a crisis, but factor in the cost. The shark brake design is prone to corrosion from exposure to the elements. I have seen a stainless steel replacement kit (brakes and rotors) for around $700. There may be better, less expensive options out there.
3. An owner who starts up a car before you see it could be hiding leaking valve seals (it would smoke when first started after sitting a while) or some other starting problem. Be skeptical.
4. IMHO, you must take it for a drive before closing the deal to at least give the engine and transmission a rudimentary checkout. Better yet, drive it to a known, trusted mechanic and get his/her assessement -- particularly a compression check.
5. What Nut said is true. There are plenty of 78 SA's out there. And, if you are not necessarily locked in to that particular model you have even more choices. Odds are, the seller doesn't have a lineup of potential buyers grabbing for their checkbooks. Take your time and make sure its the right one for you.
6. Go to
http://www.corvetteactioncenter.com/tech/buying.html There is a very detailed buyer's evaluation form there that will at least give you food for thought when looking at this Corvette and others. And, it will help you remember exactly what it was you saw.
Sorry to be so long-winded, but I've looked at several 78 SA's and Pace Cars and, after sleeping on it, find that I have rationalized some of the shortcomings with each one I have seen so far. So -- still looking. :crazy
Gook luck!