A 1" worked perfectly for to hold the camshaft when I took the sprocket bolt out--the 1" actually needed to be tapped in a bit to grasp the nut, which made a real secure lock. I can't see 15/16" working. Have a torque wrench too, one that goes up to 130 lb/foot...You'll need someone else to hold the wrench and you'll need an extension for that wrench; 130 lb foot is a helluva lot of torque.
