[Wynand]

I had sent my chassis for a proffesional shotblast and when it came back I immediately sprayed it with lead oxide primer (thinners based) followed by a two pack epoxy.

BTW, the chassis was originally cleaned with acid rust removers et all (instructions followed to the letter) and epoxy primer sprayed and after sitting in the garage for a few months, rust formed under the paint and lifted the paint resulting in some cancerous spot all over.
Then decided to do it the proper way and one really need the surface preparation (velcro like) shotblasting produces for the paint to adhere properly. Done a few months ago and chassis still perfect.