Its obvious these are fake based on the fact that they just aren’t period correct German stamps. The one on the receiver is fantasy style waffenamt, and a depot reworked M44. wouldn’t have a waffenamt on the receiver, thats the sort of thing you see from original production. The marking on grip is just a Reichsadler (Nazi eagle), which were only used as firing proofs. Actual captured reworked rifles will have a depot specific waffenamt or some other unique marking on occasion.
I don’t know where you are getting your other opinions wrong, but anyone who says this is original doesn’t know what they are talking about.
ps. RIA and other big auction houses are not a good resource for information on German arms. They all sell bs German rifles all the time.