In 1969, restrictor plates were placed on the Ford 427 and the Chrysler 426 hemis. The Ford opening was 1 1/2 and the Hemi was 1 1/4, which gave the Ford a total of 1' more opening. There were none on the Chevy's.
NASCAR finally banned the Hemi and the SOHC Fords so Shivey could keep up. Ain't a put down of Shiveys, just the truth. Bill France wouldn't let them run the Hemi or 427 SOHC Ford, so a lot of round track boys took off a year and went drag racing
Make them take cars off of the show room floor that are standard V8's from the factory, keep the original body only making adjustments for aerodynamics and safety (removing glass and putting plexi in, roll cage etc) and engine enhancements just like the sport was intended to be.