If you like his looks, I'd say leave him that way. You can always find another to paint. C-3PO was a figure they made a lot of, he was available throughout the whole run of the vintage line, and had 2 versions, the regular and take apart to mimic the scene in ESB when he gets blown apart.
You shouldn't have too much trouble finding another. Look for ones with faded chrome, they'll be cheap, most folks want him shiny. I'll keep my eyes open for ya too.