Another vote for Steve Goff for resprays. He did a beautiful and reasonably priced job on my one and only custom 653 steel frame a couple of years ago. Excellent attention to detail, nice guy to deal with.
I can't comment on repairs but, as a well regarded frame builder, I imagine he knows what he is doing.
Edit: but, as LWaB says, replacing your down tube plus the inevitable respray could work out more expensive than a new frame.