Little late response but I used a little different approach with phosphoric acid. I agree that bare metal followed by epoxy primer is best. In my situation, I worked a little bit everyday for 4 years. I body worked each piece one at a time. When bare I scrubbed it with phosphoric acid leaving a lot on the part. Next day I hit it again, this time wiping off all the liquid I could. Stored the parts this way for 1-4 years. Used scotch brite pad to clean before primer.
No rust in between and paint is still perfect 4 years after painting.