I'm thinking I'll try to clean it up a bit and ride it for a while. If I really like it I might try to do a proper repaint to match the fork, assuming I can get the fork usable again. Right now there's a chunck of stem stuck in there that's shorn off in such a way that I can't get a grip to try to wiggle it out.

It would be nice to ID the frame, but maybe I'll just have to learn to enjoy the mystery.