I had this exact dilemma with an Oberndorf sporting mauser I own.
Mine was marked 80 N or 8x57 normal, but I was unsure what was normal pre WW1.
The 8x60 as I understand it was only made from 1919 - 1930's due to restrictions on 8x57 manufacture, but was also made in either J or JS bore.
If yours is a sporting mauser there will actually be some numbers underneath the barrel which give the bore and groove diameter of that gun.
The common advice is get the bore measured to determine which bore it has.
HOWEVER, this is not entirely correct,as both J and JS bore can be around .321.
The advice I received from a well known guru on mausers is that the CHAMBER NECK is actually the critical dimension.
In the J bore it was naturally smaller and firing JS ammo in it can build pressure due to lack of room for the neck to expand.
Mine turned out to be a J bore ,however as was common the neck had been reamed out early in the rifles life to convert it to fire JS ammo.
I am picking yours is J bore.
Get it slugged to be sure and in particular have the chamber neck checked.
If you want I can send you a copy of his posting,
GDU