Hey Bob,

ESCA is not an SCCA club so we have a lot fewer classifications. And most mods don't affect a class change. So with or without the pulley you'll be in GTA-S. The "A" is for 8 cylinders or 6 cylinders with a turbo or supercharger. The "S" is for street tire vs an "R" for race tire.
And yes, the club has loaner helmets. At the meeting tonight I'll check to see if your application has been received yet.

Also, I'll bring some tape that we can put on your car for your # which you'll get during registration.