Any experience with or recommendations on restoring rusted galvanized steel?

Hi, All, Some of the equipment I have has been through the wringer before it got to me so I have a couple of items of unpainted, galvanized steel where the galvanization is gone in patches larger than your hand and the steel underneath has oxidized to black (not so bad) or red (not so good). At the moment, I'm dealing with a single-board-computer "base" and a semi-custom rack shelf that both need some help. I know I can treat red iron oxide (rust) with naval jelly, but then I still have bare steel with no galvanization. I'm not expecting to get a cosmetically perfect item, but is there a good way to restore/protect things like this, or should I just expect to paint the entire item (it would look strange to just paint the formerly-galvanized area). Obviously, descaling, sanding and painting is one way to deal with this. I'm looking for possible alternatives. Thanks for any suggestions or pointers, -ethan