I think the question is: how clean are you going to be able to get the metal first? It's my understanding that epoxy (or any other basic paint) over any rust (surface rust, pits, etc) will fail with time. If you can't get rid of all the rust, I wouldn't cover it with epoxy. Similarly, I don't apply POR15 over pristine metal, that's not how it's supposed to be used. Fortunately, that area won't be exposed to much moisture so which ever way you go, it's not likely to cause much problem in the future. I've never had POR15 fail me when used appropriately but I don't like painting over rust. I'd get rid of whatever rust you can. Whatever you can't get (in seams, in tight corners etc) I'd dab on POR15 before it dries completely, mist the POR15 with a quality primer and topcoat everything with whatever product you want. To be honest, if you get the metal real clean, a spray can enamel should provide adequate protection in that area.