The prototype kit car was a Challenger that Dale Earnhart helped test and I think I've seen Dart Sport/Duster versions, most were F-bodies, but don't recall seeing a "real" '72 or earlier A-body.
The Scamp is just a re-boxed Petty Dart. The AMT Cushman duster uses what looks like a camaro bumper but using it's front is probably good enough for making a generic short tracker.