As regards the second rifle with the 4/xxxx serial number
I have no idea if this is true but back in the late 1990s there were a few od variations of No4 MKII rifles in PA that all had a similar look:
1) The old markings scratched out, including the serial numbers.
2) the metal was bare or looked like it had been re-blued and then handled until the bluing was gone. These rifles did not seem to have the park/suncorite look
3) two serial number patterns: A) metal stock disc and the serial number on top of action body, 4 digit xxxx
B) serial number on butt and rear of action body, with either a 1/xxxx (if SMLE) or 4/xxxx (if No 4)
4) stamps on action (two I examined) were Faz 49
In any case a chap told me these were rifles supplied by SA to Rhodesia in the 1965 to 1970 time frame, the ones with the stock disc being police guns and the other ones being military or some sort of armed guards. I believe the guy who told me was a expatriate from one of these no longer existent nations.
Never seen that in print, but thought I would add that to the mix.