Nice rifle. I bought a 9.3 x 62 type B in just about the same shape a couple of years ago but with no game dept history. I scrubbed the barrel for several days. The first time I fired it, bullets key holed at 25 yards. I don't know if I ruined the barrel with aggressive cleaning or if it was already gone. You may want to fire yours before you finish the cleaning to see if it shoots round holes.

I ultimately sent the rifle to G&H for rebarreling and restoration. They did a very nice job. Will post photos if I can remember how. Good luck with yours whether you restore it or not.