In another thread it was noted that Sun rims usually had a slight overlap at the bead. It was suggested I'd have to file them smooth, and I balked for a while because of scratching. Well, there was scratching, but I went after it with some 1000 grit sandpaper. Don't know if I did it right, wondering what grit-equivalent finish these rims are machined at, but I think they turned out pretty decent.
Before and after;