I coat all my rust repairs with Hammerite. It works just as well if not better than POR-15 or that stuff that Eastwood sells. It's a whole lot cheaper. You put two solid coats on and it lasts forever! I've used it on everything from my 620, Triumph, Rambler, '49 Chev, '55 Buick... it does a super job!
Get the stuff you can brush on.... put it on nice and thick!