I picked up an old Fuji that I want to repaint. Easy way to take off riveted headbadge without f'ng up badge/frame?

I thought the same thing as well. I have a World Sport that has rivets holding it on. Knowing what I know about rivets, you can use a drill bit that is slightly larger than the rivet hole. Just drill it carefully and it should dislodge the top cap. Once that cap pops off, then the badge should fall right off. Then re rivet when you are done with your re build. The holes will already be there from OEM.

masking tape. Unless you have access to nice painting stuff it's going to look like **** in a few weeks anyway