Getting ready to paint undercarriage of 70 Gran Coupe, have spent 2 months cleaning off undercoat and ready to sandblast. The car has little rust, but does have some on frame rail under the master cylinder. After sandblast and prep with KBS Aqua Clean, I'm ready to prime. Is it necessary to use epoxy primer or is reg primer ok. I just want to do this once in this lifetime. Car will never see a trailer, but I will be careful when I drive and watch the weather. Epoxy vs. standard primer, that's the question. I know if I use epoxy there is a recoat time frame and not sure if I can recoat that quick. What's the verdict?? Or is there a better mousetrap? If I find an tutor, I hope to post pics of rebuild on this site to humor everyone.