Depends on whose races your running. National rules are set up.
http://www.evansvillekia.com/nssna-nss-rules
Most run on these rules. If you're legal for these you are pretty much legal anywhere. Basically NHRA safety rules for cage/bar, upholstered interior (don't need rear seat), 10.5"max tire, Big block or Hemi, 727 or stick, 5" max period style scoop or no scoop, no electronics,air shift, trans brake .There's others running looser rules as well.
NENDRA(North East Drag Racing Association)is opening up it's rules for 2013
Just want everyone who is interested in racing with NENDRA next year up at Lebanon Valley,NY and Island dragway in Great meadows NJ.
NENDRA is opening up their rules to allow modern hood scoops, transbrakes,big slicks.
As long as your car is Detroit built from 1961-1973 and it has a stock looking interior you are welcome to join the group. PM me if interested. Usually 12-15 races per year.