It's been a long time but IIRC, CMC cars fit into SCCA Improved Touring and/or SCCA regional classes. I suppose choice comes down to what you are interested in - fun for the weekend, a trophy, season points, etc.
If you are interested in other run groups, check your local track schedules and show up as a spectator and ask around.
I have run EMRA many times and enjoyed it, but they are a little too far east for you.
http://www.emraracing.org/I current play with these guys (when my car actually runs) and though they started out as a stock car group, they have had Corvettes, Mustangs, etc. They piggyback on SCCA events but aren't tied to any region and make up their own season schedule and points.
http://v8stockcarnorth.com/V8forum/index.phpYou might want to sign up there and start asking questions...