Just tossing this out there as another option......If you have a company like Redi-Strip in your area they do a chemical dip that removes all rust, bondo, paint, etc....Only metal remains when you get it back. They told me that it has a film on it to prevent flash rust. That film is removed with water, then you let it dry for a few days before painting. They quoted me about 800-1200 depending on the condition of the item.
For years Redi-Strip has been the top choice for metal restoration and paint removal services among metal stripping companies throughout the United States.