That seems like an interesting gun and I hope you enjoy it very much. A word or two of caution, from my experience: If you haven't figured our exactly what rifle ammunition your drilling takes, you must do a little research. There is no such thing as a generic "8x57R" cartridge that fits in those drillings. Most old ones were made with a .318" bore, and of course for the rimmed version of the cartridge. That is 8x57IR or 8x57JR ( I and J are interchangeable letters in the original German script ) More modern drillings are all made for the 8x57IRS or 8x57JRS and have a .323" bore diameter. USA made 8x57 mauser rimless ammo is likely not appropriate for your rifle. That ammo is made with an intermediate size bullet and low pressure, to allow it to be fired in either bore size bolt action rifles. "8mm Mauser" ammo does not have a raised rim for break action rifles to extract the cartridge with. I had a nice old Sauer drilling in 8x57IR that was an exception, which had a neat dual purpose extractor, the old .318" bore, and could fire mild USA made 8x57 "Mauser' ammunition safely.
Regarding claw mounts, you might get lucky and find a mount that fits your claw base, but claw mounts were made to be individually hand fitted, a technology that predates our mass market expectations of interchangeability of parts. it would be random chance if you could find a claw mount that fits your gun. All the new claw mounts that I'm aware of are made oversize and must be carefully and meticulously filed to fit. But you never know, you might get lucky. Or pay the $1500 or so to have a new set of rings fitted by a traditionally trained German gunsmith.
I've had good service for my 65MM chambered 16 ga. guns with Gamebore Traditional loads. They are very good quality and match original specifications for older guns.
I hope you get to take your drilling hunting soon, they are a wonderful, versatile gun!
