I agree with that, except that the rims were painted in enamel, where the body was in lacquer. At any rate, my research on earlier cars shows that the "dog dish" cap was not optional; it was the standard hub cap. If a combination of white wall tires AND a full wheel cover was ordered, then the wheels were painted black, otherwise they were body color. Now since a SuperSport automatically came with full wheel covers, if white wall tires were ordered, the rims would have been black, but IF the car was built with the standard black wall tires, I'd suspect it would be delivered with body colored wheels.
It's very difficult to tell exactly how a car was sold new if it was a "stock" car rather than an "ordered" car. Dealers routinely made changes to their inventoried cars to make them more attractive to buyers. A very typical change would be to add full wheel covers to a car, thus making it look much better on the lot. (not like a cheapie) None of those dealer changes would appear on ANY paperwork.
Verne