DaveWp, if your "elsie" 16 ga is a Field Grade, is it a FW (Featherweight) or Regular Frame? You cannot interchange one from the other. The Regular frame is bigger.
Even if it is from the same frame size stock, all L.C. Smiths were hand inletted. You might get lucky and have one fit from another FW gun, more likely you will have some hand inletting to get the side locks to fit correctly to the new stock.

David