Again, what exactly are you going to be repairing? You mention "pin holes" in you last post, that isn't all you have is pin holes in welds is it? You certainly don't need Duraglass or even regular filler for that! A little polyester putty and you are done.
Polyester filler will stick to bare metal just fine. The epoxy is an added corrosion resistance for you. Epoxy has a sticky resin that likes to have things applied over it with no sanding