The one and only time my '36 was repainted which was in 1961, it was painted with black Duco Dulux, a single stage enamel. We did some minor repairs to the running boards and then painted them with the Duco Dulux.
There is a wear pattern in the rubber at the center of the boards from years of people getting in and out of the car, however, the enamel paint minimizes the appearance of the wear because the ribs are still faintly there. I make it a habit to never step on the boards, telling anybody that gets into, out of the car, to not step on the boards.
I bought a new set of boards from Drake a few years ago when he came out with them for the '36's, they are sitting on a shelf in my shop. Might put them on one of these days.