With that early Mauser commercial serial number and being a small ring action, you have probably got an early rare "transitonal" action instead of a Kar98a one. Jon Speed lists transitional actions up to serial # 3209 of Mauser's commercial serial numbers. according to his list the action #1125 is dateable to 1899. Can you please post a photo of the boltsleeve. It should still lack the bolt sleeve lock on the left side. But I would still not hesitate to rebarrel it to 9.3x62.