Perhaps it is just a trick of the lighting in that particular photo, but if not, I would be concerned by what appears to be evidence of a rather hefty bash on the edge of the receiver ring.
On another point, the only Sterling conversion in the collection was performed on a No. 4 Mk I (T) (I know, sacrilege!), and I notice the 7.62 barrel is without bayonet lugs. Previously I thought all Sterling conversion kit barrels were "lugless" as well, but as Sterling was hoping to get a contract from the Indian Government to convert their No. 4's, it would make sense that they would provide accommodation for continued use of the bayonet. Are there other Sterling 7.62 conversions out there in Collector World with bayonet-lugged barrels?