Well I think most of the people you talk to that has had a truck/car done for a while had their frame powder coated, which by no means have I ruled out. I know that my brother-in-law that has a 66 mustang fastback keep saying to do go the powder coating route so it is definitely a solution.
Oldsub mentioned Por 15, which I don't know anything about and once I hit submit I plan on doing some research about it.
Doc bob to answer your question no I haven't seen a galvanized body but do you know if it was a cold galvanized? Also could you send me a link to some pictures of your body? I would like to see it or was it panted over? I think cold galvanizing is what Lonnie is talking about with the electo-plate galvanizing but I'm not sure as I don't know anything about electo-plate galvanizing.