While I know there are hundreds of posts about rust, I'm asking for specific advice here. The only rusty part of my 83 Miyata 610 is the chainstay (SEE PIC). Must have had some major chain-slap going on! The rest of the bike (including insides of tubes) looks pretty good, so I was not thinking about the oxalic acid "bath" I've read about here (but have never tried).

If you have had experience with a localized problem like this, I'd appreciate any advice---both how to treat the rust, and what to do with the surface after. I am not seeking a museum-quality restoration here, just protection and good-looking, functional approach.

THANKS!