I did similar to what KevinW suggests... and my pipes look similar to his. I ran sandpaper over the outside to remove the loose stuff, then sprayed with Dupont metalprep, then washed, dried, and painted with a silver color high temp exhaust paint.
My goal was/is to *preserve* the life of them as long as possible, and prevent further deterioration from the outside surfaces. The pipes I did this too were purchased from Chevy parts department in 1976, and they still looks pretty good.
My one area I'm going to have to *work* if I put the original exhaust manifolds back on is the header pipes, as I cut them to mate to headers back at that time. Any suggestions as to where to purchase the *most original* head exhaust pipes?
