I think the Simplex derailleur will still work in that Southpaw, but the rear bolt with shoulder might be a little loose after the threads are cut. Trying to avoid doing any grinding if I can help it. Tinkering earlier, I noticed a claw might work aside from the fact that it moves the derailleur outboard a bit too far I think. On a fairly narrow range Nuovo Record derailleur there doesn't seem to be enough adjustment between the stops to use a claw hanger. Thanks BG, I was aware of the modification but shying away from the grinder. And thanks Colonel. Going to look at that Crane and see how it works. Does it have a custom stop clip built into it that rides on the circular outside diameter of the Simplex hanger?