I'm doing NASCAR, or possibly a USAC Superbird from the JoHan kit, using the AMT GTX kit for the chassis. the JoHan kits can still be found and at a reasonable price, but it may take some time and research. also, you don't need an entire kit, only the body, nose and wing. just about everything else can be lifted from any one of these AMT kits: Dodge Superbee, Plymouth GTX, Plymouth Road Runner and any 68-70 Dodge Charger.
best of luck to you with your build.