I would love to see the Firebird (in Formula Trim!) in all it's body styles, the Fiero Formula (V6 please), Grand Am, Bonneville, and the GTO. Then I'd like to see cars like the Dart, Nova, 442, Grand Sport, GTX, Chevelle SS Cudda, El Camino and the Fox Body Mustang.
I'm not a fan of American cars as of late, but all the cars I listed (except maybe the Fiero/Fox Body) had a big impact on the car world. I would defiantly trade a few MX-5/GT-R/S2000 model types for these cars.