Drill and tap them from the original #8-32 to #10-32. Run your tap drill through then your #10-32 tap. Be sure to use aluminum tapping fluid for a good cut. No need to drill a clearance in the head side of the mount. The new threads aren't enough to bind the screw. Then find some #10-32 socket head cap screws of the same length as the original screws. The heads fit perfectly. They won't strip out now. I do this first thing to every BKL mount I buy.