I would have no reaction to you changing parts to other period parts on any American rifle unless it was sgt york’s personal m1917.
I’m Canadian, and same answer if it was a Canadian rifle.
I have not done anything irreversible, I have the two removed parts stored safely with this rifle. A ground volley disk and a non-milled sight protector. I’m changing a few other parts of no import, like screws with buggered up slots and a bent up unmarked sling swivel.
As for the rifle’s markings, the butt is original, unsanded. Marked 1/1916 (an issue date, I think), the original bsa serial number in a ww1 font, HV and 2MD. Nothing after that except the 1913 era bsa inspection stamps.
I think all it got was a new barrel in 1929 and the volley disc ground.
So to each his own, but this is a Britishcommonwealth rifle in decent shape with no permanent changes. Definitely not worth your brusque criticism in my view.