The rifle is of typical pre-WW1 Suhl design. These rifles were made by the guntrade there for all the "name" and "country" gunmakers. A look at the proofmarks under the barrel will allow closer dating: If the bore diameter is given as a gauge number like 108,49 or 118,35 it is pre-1912, if given in mm like 8,9 it is post, then there is also the possibility you find a proof date like 7.13 for July 1913. Most of these sporters are made on commercial Mauser actions. Before WW1 the Mauser patents were still valid and there were no military surplus M98 actions, so everyone wanting to offer a M98-actioned rifle had to buy in the action from Mauser, Oberndorf first. Mauser supplied their actions to the worldwide guntrade then, not only German ones like Sauer&Sohn or Haenel, but also to Rigby, Holland&Holland and you name them. Mauser did not mark these actions on the outside, but all got the Mauser commercial serial number on the underside of the receiver behind the recoil lug and on the rear wall of the magazine. If you find a number up to about 82000 in these places, you have a original commercial Mauser part. Pre-WW1 Mauser sold about 70% of their commercial production this way as actions only before 1914. As these actions were bought in in batches and the Suhl makers disassembled them first, you often find mixed Mauser numbers on receivers and magazines.
IMHO the bolt, at least it's sleeve was replaced at a later date, perhaps on scope mounting, as they are not engraved the same as the other parts. I know another such rifle in 9.3x62 signed by Otto Bock, inventor of the cartridge, with mixed Mauser numbers and a earlier transitional bolt, but also with a later bolt sleeve.
I would not bother about the slotted receiver ring with a moderate pressure cartridge like the 9.3x62. At least, Mauser themselves used it on their scope mounts. It only was frowned upon long after WW2 with the common use of "magnum" loads and individual gunsmithes cutting the notch too deep, sometimes into the barrel threading.
The old claw mount were individually made and fitted, nothing being standardized. Fitting new rings to existing claw mount bases is often impossible, at least very expensive handwork, requiring a craftsman knowing about the job. I would suggest: Replace the old bases with EAW or Recknagel pivot mount bases, then you may mount any modern scope without worrying about eye relief and length of scope.