FWIW - a #3 Smith will fit most any holster built for a Single Action Army or Schofield - here's a Russian in a holster originally built for a Colt SAA with a shortened to 6.5" barrel, The S & W models all built on the same basic large frame include: Americans, Russian Models, Schofields, the New Model Number Three, and the .44 Double Action
Since most period makers seldom molded to the gun, neither do I unless it's a copy of one of the very few heavily molded ones such as can be seen in Packing Iron. I've sold several holsters for S & W large frames using my SAA pattern since I don't have an S & W handy and just shorten the tube up to fit the barrel. As for molding it's easy to do and those customers that wanted it done for guns I didn't have or can't get a mock up for, I was able to explain how-to using a plastic bag wrapped around the gun and dampening the inside with rubbing alcohol - never had one complain yet, in fact most have thanked me since they then could do it to any holster.