NIC Industries in Oregon, of which Prismatic Powder Coatings is a division, has recently come up with a high temp coating that they claim will stand up to header heat. Comes in a wide range of colors and many samples I'd seen at their booth at a Chicago trade show last fall were higher gloss. You have to be certified by them to apply the stuff. I wanted to pursue the certification for our shop but fortunately for our powder coating business, have been too busy to get away for a couple day training class. Sorry I don't know more about the process involved.

You can contact them to find out if anyone in or near the Bay area has been certified. It would likely be someone who already does powder and/or ceramic coatings. Just do a web search for NIC.

Your powder coater is correct in being concerned; best current high temp powders are good to about 1200 degrees but limited in color options to pretty much flat black and silver. Conventional powder coatings will start to fail after they've seen 400 degrees for any extended period of time. Usually they lose gloss, then adhesion in this situation.

Hope this helps.