Now that I am getting close to painting, I started looking at the underside of the hood. We did not blast it, but it is totally smooth on the top. But, underneath, it looks awful. I was thinking of some kind of insulation, but I can't find something specially cut for it. Any suggestions for insulation or a liner coating? It is a '53 bolt about to be loaded down with primer coats and four coats of red. (but not under the hood).