In the southeast "oddball" cars commonly run in SPU or SPO. Over or under three liters.
Best part of the SPO class is no protests! Other than safety equipment, rules are open. I was told by a guy with a chevy that had formerly been in GT-1, that that's why he switched classes.
Would you win in that class, don't know, but you've always have someone to race with as you'd run with the other big bore classes. Great to hear you're motivated!