I assume that Kuhnhausen's book on Mausers is not in your library ?

http://www.midwayusa.com/product/66...8-a-shop-manual-book-by-jerry-kuhnhausen

It's VERY clear that the only SURE way to ID a Mauser action is measuring between the guard screws and having accurate photos of the various action types.

You can find Mauser 98 variations with marks on them from Arabs to Zimbabwe.