Judging from the bolt handle, the bottom metal, fore-end checkering pattern, and the stock, the rifle may well have been a Mauser Model M Sporter with a full length Mannlicher style stock in caliber 6.5, 7, 8, or 9X57.

If it were mine, I would rebarrel it in caliber 9X57 with a 50 cm barrel turned to the original profile, and find someone to restore the stock to its original configuration. A magazine intended for 3.07" length cartridges will require lengthening to accomodate an 3.35" .318 Westley Richards. Caliber .358" bullets are much easier to come by than the .330" bullets used in the .318.