I’ve started a frame replacement for a 70 El Camino. I picked up a used frame that was cleaned up and coated by previous owner. My assessment of the present coating, POR 15 is there was not enough thickness to cover the rough surface prep. Also, POR 15 doesn’t like ultra violet rays and tends to chalk. As such, I want to clean up the frame and over coat the POR 15 and also protect the areas of bare metal that shows through the POR 15. I’m looking for suggestions, should I just prime over the POR 15 and bare metal after a good prep and cleaning? What do you think. Trying to save money and still get a good looking job that will last for years.