This is my thinking too. My research has found that the government conversions usually had all the bells and whistles: charger guide insert and spring loaded ejector nub installed, at least according to BoTR who produced an excellent video on this subject. Kits that were installed by civilians quite often lacked such refinements although most if not all had bayonet lugs and a Parkerized barrel. I have a spare No.4 Mk I with a shot out barrel so if I'm the winning bidder and this rifle has issues I'll swap out receivers.
Regards, Derek