When I stripped my 1985 Team Fuji down to chrome, I noticed the same sort of rust spots in the same location. I suspect that it has something to do with the brazing process. What I did that worked pretty well was to sand the rust down a bit with a Scotchbrite pad and then touch up the areas with Testors silver paint. I really helped to cleanup the frame. It's not a perfect match, but if you work to blend in the paint, it ends up looking like a roughish area in the chrome.