In 1964 I sent sn 196 or 194 back to the factory to have a single trigger and ejectors installed. I also ask for a new stock with checkard panels like a trap grade. The gun came back with the frame reblued and a new beavertail with the diamond pattern.I have no doubt they would have engine turned the flats and forend if I had ask.
The engine turning looks factory and with that low sn and the diamond pattern and the brace it my have gone back like mine.

AC