I do think it's been sanded rather heavily before the shellac was applied, at least that's what the shallowness of the wood stamps seem to show...
Do have a really good close up of the top of the bolt and the serial number "1973" stamped on it?
Also, if I read the writeup on your wood markings correctly, there is no serial number stamped inside the hand guard or stock?
Here's a link to a small photo album I have of my BYF 1945 example...
1945 byf K98k Mauser - Badgers Photo Gallery
Regards,
Doug