The Black and Silver "Pace Car" paint job was on the 78 Vette, and when done on any early C3 Vette it sort of gives it an updated look. IMO
You're right about 72 Chevys not coming in black, all that was offered was a very dark brown metallic instead of black.
I think the biggest frame rust problem occures just in front of the rear tire where the frame starts to curve up over the IRS.
Sometimes you can have a noisy rear leaf spring, but installing the 1 piece 81/82 "Fiberglass" spring is a permanent fix.
Thanks to the cruise control, it was very easy to disconnect the speedometer cable on these cars. So that often explained why there were so many incredibly low mileage Vettes back then. (Not implying your friends Dad did such a thing), just saying many owners liked to keep the mileage as low as possible for resale value. Being as old as it is, hard telling how many owners it had in the last 41 years.
Brake problems were very common, again because many Vettes really were super low mileage cars, because they sat for long periods of time. Old style brake fluid held moisture and corrosion happened.
If the car has synthetic brake fluid that's a big +, updated to stainless steel brakes is the best mod.
I've had 7 Vettes. 78,80,81,84,85,86,87. I actually enjoyed the C3's the most.
Like Doc, I'd give anything to have a 67 Coupe, but they are so far out of my price range that will always be an unfullfilled fantasy. I actually had a guy that considered trading me his 66 coupe even up for my Viper last year. I only hesitated because his car had a "Powerglide" tranny. In the end, I decided I needed the money more than the car, and he finally sold it, and I sold my GTS.
I hope it works out for ya, they make a fun cruiser, and really aren't too bad on a curvy road.