I'm installing the original cast iron intake back on my 383. I bought a valley gasket and some fiber gaskets that were listed as needed to go with it. I have two questions. First, are the fiber gaskets optional or necessary. My past experience w GMs makes me think they are optional? Also, the old valley pan that I pulled off, had what looked like fiberglass insulation sitting on top of the pan. Wondering if that's optional as well? One, more question. Do folks paint the top of the valley pan? Seems like it would rust otherwise.