Since these parts were hand fitted don't expect them to be interchangeable without refitting
The design evolved throughout production.
The parts are specific to either feather-weight or regular frames.
A hammer gun didn't have a safety but I suppose you could modify it although I wouldn't recommend making modifications to safeties.
The plates with the two holes were used only on early style plates which didn't utilize the bridge, as far as I know.
If you're going to hobby around with these guns I highly recommend acquiring a copy of Plans & Specifications Of The L. C. Smith Shotgun by William Brophy; it will allow you to identify parts and provides drawings when necessary to fabricate them.