I'd sand down some of the rusted parts on the out side only, and/or the inside and recoat with plastic coat if you know what I'm talking about, sand down till you can coat it with plasti coat and still have clearance, I'm a miser with money!
I don't care about looks and you can use the orange color or what ever else you find, the last time I bought some was in the 90's though at Walmart, it came in like a 6 ounce jar. Its like for projects and things, you might find it in Hobby Lobby near the model airplanes and things.