Steve,
Oddly enough, not all actually did. I located a '69 SS427 green/green auto in Andover Auto Parts (the same place I located a Z-16) in MN in 1979. I still have the POP for the car and a friend now owns the engine. This car had the 335 hp 427 AND Drum brakes????? It is the ONLY one I have ever found this way. Odd situation. There was no way to verify if it was a real Z-24 but the car was bone stock and still wearing original paint and had ALL the SS emblems on the car including the steering wheel. I still have the emblems off the car as well and they did not appear to be added on.