You will eventually see rust on the frame, no matter what you do. I had my frame sandblasted and cleaned it after bringing it back from the blaster, shot it with epoxy primer and black semi-gloss enamel. There are spots of rust, especially at the riveted joints and spots that are extremely hard to get to. A rust converter primer might have been better, but unless you dip it in a huge tank of paint, you'll never get it everywhere. Do the best you can and don't stress over it.