That's a great bike, and I don't think I've ever seen one like it. If it were mine, I'd start looking around for a saddle that's worthy of the bike and its vintage. If you're going to tear things down, you can remove the rust from chromed or painted steel using an oxalic acid solution (search for this on Google or in this forum), but don't use it on aluminum alloy parts or zinc-plated parts (some fasteners, for instance -- zinc is quite reactive and disappears in a big hurry with that stuff.