I'd like to open it up a bit more too. Perhaps change the class name from Muscle Cars to 60's/70's Aussie Tin Tops or similar? That way Moffat's Escort (I like the look of Manimmal's) could get a run and some of the other cars that ran with (not against) the Stangs and Camaros...?
The Escorts don't turn as nice as the Stangs and Camaros, but leaving the FF motor in would even things up a bit on the straights, wouldn't it???
Come to think of it... Yes, parity allowance a must.