Craig, it could be so, yes.
The rifles chosen for conversion were stripped, all parts gauged, and parts passing spec were retained for use on the prod. line. New parts were used when required. I have seen original matching nosecaps on HT's, I have seen un numbered nosecaps too (because there was a standing order the rifles were not to be stripped with any other weapon on the bench, to prevent mixing up of parts, it was not a requirement that replacement parts be numbered.) I have also seen nosecaps with a struck through serial number used. Some might think this a but suspect, but when the struck number is off another HT it shows the parts which passed muster were re used.
Now, for the mod to the nosecap ears... I have 200 rifles in my survey. Of these I have answers to the nosecap mod Q on well over half, so a fair sample, near 10%. Of these 1/3 have had the nosecap mod done. I would say with reasonable confidence that between 25 and 30% of production were done. It would not have been done at time of conversion, rather already in the system or on the rifle.