Just to add...

This mob are great to deal with, at least from this side of the pond:

https://vintagegungrips.com/shop/mauser-buttplate-curved-5-14-x-1-2132/

Used to be called Vintage Gun Grips, now Triple K Manufacturing apparently. Used them as recently as late last year for Colt revolver and Browning auto grips. I'm a happy repeat customer going back maybe 20 years or more!

Presume they were the source of your plastic butt-plate, K98?

Unfortunately they don't appear to list the earlier-logo butt-plate. Perhaps someone should send them an original to copy!