RE: Most stable scope mounting system???
Leupold makes a one and two piece base. This is their standard bases that use the dovetail front and windage screws in the rear. They don't make dual dovetail bases for a 98 mauser.
Talley makes a set for a 98 mauser. This is as good as it gets in scope mounting but you will pay for it. About $100+ for a set of rings and bases.
Honestly I would use Weaver Grand Slam bases and some Warne rings. This would make about a rugged combo as I could think of and still not empty out your wallet.