I found an old Canon XI 100mm f1.5 lens in a secondhand shop in Tokyo, and after a quick freelensing felt that it was worth adopting. Flange distance is quite short, but after some work reaming out an M65 helicoid, have managed to get it to focus to about 5 meters on a Sony A7RII. This seems to be another of those X-ray lenses, which usually very glowy with spherical aberration, but this seems to be a different beast, and is quite sharp on top of it. It does get less sharp in the corners, but has a nice quality I quite like.