I found some cheap bodies.
They are
Blazin' Key Cars from Irwin Toys.
The packaging says die cast metal chassis, and it is, but the body is plastic. I got three at Job Lot (the local overrun and defect outlet) for $2 each. I got the Viper, the Corvetter and the Plymouth Thunderbolt... it's not a prooduction car, but it had the most headroom) The bodies are screwed on so you need to dremel away the screw mount. But, they are a close fit. The viper's wheel base is almost exact, but the others need some carving, you'll see the big wheel wells from dremelling on the white car (Thunderbolt). The vette will need some dremel too because of its long wheel base.
The bodies are longer than a ZZ, so I haven't figured out how to mount them yet... I'm going to need to glue something onto the bodyto meet the tabs. And, not shown here, there are slots in the back of the car for the key that the car comes with. I guess I can fill that and try to make it look right. Either that or just not look at the back of it.
edit: oh yeah, the bodies are shallow, so they might end up sitting a little high. I think I can get the Viper to sit as low as a regular ZZ body, but that's with a lot of carving, and that's still high, IMO.
Anyway, thought I'd throw it out there if anyone is interested.