Redoing a 80 z28 with some patch panel rust repairs. This car is in original paint so was wondering if I could sand down to original primer then go to my poly surfacer to block before the 2k then Bc/cc. Any bare metal from weld repair I was going to hit with Eastwood Epoxy primer in a rattle can before the poly surfacer. Is that a sound plan or does it all have to go down to bare metal. Thanks for the help.