One other thing you might try is epoxying the scope-mount base to the action. I know more than one gunsmith who's used this trick to deal with 98 Mausers where a screw-hole can easily be buggered, or even become slightly loose, because the thin bridge wasn't originally designed for scope-mount screws. In fact, this is the way my .375 H&H Mark X Mauser's rear base is mounted, using Acra-Glas Gel. If you decide to change mounts later, it can easily be removed by heating the base.
You can also have the mounting holes converted to larger 8-40 screws, but that doesn't solve the problem of very few threads inside the hole, which often causes the problem in the first place.
