You might try Cylinder & Slide in Nebraska. The problem is parts. For example, the cylinder stop design used in this gun was last used over 50 years ago. Also any new part likely would have to be fitted.
Technically, a 625 cylinder could be fitted. Barrel also. You are going to have cosmetic issues where the barrel joins the frame. Also, you will probably have to do something with the front sight to get it to shoot to point of aim.