I would say that if the cage is red the floor would be too. If you lurk around Randy Ayer's NASCAR site I'm sure someone there would know.
http://www.randyayersmodeling.com/
Cool model, love the diorama as well. Me and half my high school class learned to drive in one almost exactly like this thanks to it's owner, push-button auto with a slant 6. Thanks for the memories!