I am wanting to paint my trunk. It has some light surface rust in spots and some por-15 in others where I have worked before. I have decided to clean it up and splatter paint it. Should I sand it and primar then splatter? What process would be best. The rust in only in a few spots.

That is what I did. Light sand, primer, then splatter. Since my splatter is black/aqua I laid down a coat of black paint over the primer, then the splatter. Only took two cans of splatter that way. I think your 66 uses a grey splatter so it should cover primer with with no problem.