Do you mean EY or GF rifles ?
By no means were all EY rifles converted to GF rifles and not all GF rifles were ex EY rifles, but, it is fair to say that generally GF rifles were conversions of EY rifles to avoid 'wasting' a pefectly good '1st line rifle'.
Peter did post (in 2008) the following regarding GF rifles :
Thanks to former Armourer ‘Robbie’ Robertson who was able to shed light on this. Robbie also commented that ‘………….. we did about 250 of the rifles in 1967 or so but I don’t ever remember seeing any of the actual cups since Korea in the early 50’s. I don’t think we had any!’