This is not gunsmithing, just making do. I don't see a problem with a little chamfer to the cyl stop. Seems to me it wouldn't affect the other chamber notches but only drop in sooner in rotation. Before doing mods to anything I would check out availability of parts you might modify. If something you do messes up the part you will know more about replacing it. You might study the ratchet and decide what was modified and consider doing something to restore its function. I don't know about S&W but I had a Colt that I fixed a star problem by a ding with a punch.