journeymen,
The bore (not groove or bullet) diameter marked as 118.35 very often works out as .357-.359" groove diameter. This will make finding bullets for handloading easy for you. You mentioned the need to rework sear engagement. You may need to do this but rifles with double set triggers are very often found with them out of adjustment. This is usually because the purpose of the screw behind the front trigger is misunderstood. This screw has no effect on the trigger pull when not "set", only when "set". I suggest you check the adjustment before working on the sear engagement. BTW the rifle doesn't have to be cocked to adjust and/or check the set triggers. Good luck, you are going to have fun with this one. You didn't ask, but it was proofed in August 1909 at the Zella Mehlis proof house.
Mike