I would blast it with a fine media, use rust converter on what's left (if any) and charge on as normal. You can get small sand blasters (think they're called spot blasters????) from Harbor Freight that will do the small area you need done.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.