Try Joe Beatham at Gunshop East Barnet. He has a Nazi 1937 Mauser Werke made, for Portuguese Contract, 98K in 8x57JS.
These were rifles that were IDENTICAL to the German Army 98K supplied under contract to Portugal in 1937.
The only distinguishing feature between them and a Wehrmacht 98K is that they have a Portuguese crest on the receivey...yet everywhere else they have Eagle and Swastika Nazi Proof Marks.