I talked to a guy last night who suggested roughing up the surface with light blast, and coating with Eastwood's manifold coating that you bake on. We're going to try it on the heat riser to see how it works.
I had tried the Eastwood stuff before deciding to Jet Hot, and it did not hold up. You're supposed to run the engine within 24 hours, but since it was still on a stand, I heated them in the oven at the highest setting. Of course, I left them in the oven to cool, and forgot about them. My wife reminded me, when she opened the oven door to stick something in!!