The roll stamping on the rib looks very thin. All is legible, but shallow which indicates the rib was smoothed and some metal was lost in the process. I also see a slight rounding of the edges of the screw slots which can happen when buffing along with what looks like pitting on the sideplate surrounding the screws. The alignment marks on the right side frame and hinge pin look to have been buffed, losing metal and a little bit of the lines. The barrel condition is a sharp contrast to the exterior finish as we see it today. It was also mentioned above and if the original owner kept the exterior flawless, they totally neglected the bore, which is not reasonable.
Other than that, the gun is great, indicating there was at least one master refinisher still working at the repair department in 1974
(should be 1947), and did a stunning job. Too bad someone has used something abrasive to polish the surface.
I would consider a factory letter, but also you should contact the Smith & Wesson Historical Foundation and have them search for the original repair order for your gun. Link is here:
Smith & Wesson Historical Foundation - Home Page - Insuring that the rich history of Smith & Wesson will continue for generations to come
The cost is minor compared to the value of the real answer on refinish, since original guns in this condition are approaching mid-thousands in value. Hope I'm wrong here for your sake, but am fairly confident you have a factory refinished revolver.