Correct me if I'm wrong. You're looking for a S&W double action revolver, chambered in .45 Long Colt.
Hope you have better luck than I had looking for one. I ran an ad here and on LAsportsman for a couple of months looking for a 625 and the only hits I got were from dealers offering to order me one. I did see that one of the dealers had a ad for a JM version on LAsportsman yesterday.