If you're concerned about authenticity, then you shouldn't polish them. Galvanized spokes aren't supposed to be shiney. I have one set of old PX10 wheels with galvanized spokes. I cleaned them up with Brasso and then waxed them when I first got them. I don't think I'll ever do that again. It's just too much work. They're on a beater, anyway.

Galvanized means there is a layer of zinc on them to prevent rust. You can buy cold galvanizing compound in a spray can that contains particles of zinc. I have a can, but I've never tried it on spokes and I don't remember where I got it. I've used it inside bottom brackets after cleaning out rust.