Dan,
Your car doesn't fit in Nostalgia Super Stock but it does fit into the NMCA NMC class which are run off class indexes ie. 10.00, 10.50, etc.
www.nss-monster.com for rules and classes.
The car will be welcome at ant Mopar meet but they just run bracket style races. Google : Muscle car reunions and see what you com up with.
Build it and race it....that's what it was originally built to do.
Good luck,
JimR