[chris vickery]

Never used POR, seems a little expensive and troublesome to me.
A good epoxy primer is relatively inexpensive, sticks well to anything and doesn't involve any magic tricks, potions or the like to work, use or save for future use. Sandblast, wipe down with metal prep and spray, job done.
It's all I use and at the end of the day will outlive anything I will ever put back together. It's also superior to the old school red oxide primer of yesteryear.
BTW, how long was that old enamel mil-spec paint stuck on there before it was blasted off a restoration project???