In my amateur opinion it is authentic. I don't know it to be. But I believe it is. The Germans, when their K98's needed repair didn't take them back to Mauser or Styer. They were done in the field by the Army. I have seen this countless times with German rifles. Would you take your truck to the Manufacture to have it rebuilt or tune up? No you would take it to the shop. I am not as familiar with the Commonwealth's practices. But if they were fixing half destroyed rifles when would they have time to build brand new ones?
Another thing I will bring up just because it angers me is the availability of actual factory stamps. I know they make new German ones for the World War 2 era in Austria. I saw a Springfield Armory one on Ebay for stocks last night. I see them every where. That should be a serious crime. And HOW in heavens are the manufactures and armors that careless? If it wasn't for these clowns have the matching rifles that exist now wouldn't. The percentage now on German K98s is probably more like 75 percent. It's pathetic the fact they are available makes EVERYTHING a guessing game at the end of the day. Sure you can look at font's but you still don't KNOW. Font's changed when worn out at the factories all the time. I have no idea if English weapons have this same issue or not but I suspect they do.
BTW Anyone know where I can get my SMLE Bolt stamped, the importer grinded off the numbers. HAHAHAHAHA I'm seriously kidding. I could careless for the difference in money about matching numbers. I'll never pay that premium again. As long as it's period correct and everything is from the same manufacture. It's good enough for me. I also would never buy a gun I wouldn't shoot. What's the point?