Primer questions

I'm currently working on the body of my duster but don't plan on painting the whole car for a while. The metal around the windshield and under the old vinyl top have some rust that I am treating and fixing but what primer can I use that will allow me to repair spots around the car and paint later? Epoxy primer sounds like the best at sealing everything, but can I spot fix with epoxy and scuff it later on for paint? I'm thinking about a year before a full repaint.