I know many of you must be sick of me talking about "the old club in SoCal", but we solved the "classic" car issue by requiring cars to be "box stock," i.e., just as they came from the factory, with just weight and typical tuning (trued tires, etc.) being the only mods. Sure, the cars were slower than they could have been with the "right" modifications (pods, aftermarket tires, etc.), but then again, they were also "class competitive." That means that they were as closely compatible as they could be. Slow, yes. Squirrely, yes. But also very closely matched, which led to some very tight racing.
Perhaps such rules might be introduced here?
(P.S.—also cheaper than modifying your cars up the kazoo...)