If I may be so bold as to speak up (being a newbie myself), I too have been thinking about something along these lines. My proposal would be to keep all the current rules except for the following deviations:
1. Headers would be allowed but the full exhaust system requirement would still stand as stated in the current rules.
2.
Period correct aftermarket aluminum intake manifolds allowed (say 5 years either way of the car's model year).
3. Aftermarket carbs allowed with a period correct appearance - no Demon, Barry Grant, etc, etc. More or less just Holley, Carter or Edelbrock (AFB, AVS, Q-Jet replacements).
4. Aftermarket or increased capacity mechanical fuel pumps in order to feed the more ravenous beast under the hood. No fuel pressure gauges as already stated in the current rules.
I also like the inclusion of traction control devices such as slapper bars since a lot of the cars back then made use of them.
The only problem with these mods being allowed might be that it would be very hard to hook the cars up unless an 8" slick rule were invoked but then we are in a quandry as to deviating too far from Pure Stock.
My problem is my mind starts to wander and I begin to consider all the possibilities without thinking of the enforcement consequences and headaches.
Still, its sometimes fun to dream about and consider the possibilities. At the end of the day I am very happy with the rules as they are and would desire to see them maintained as closely as possible.