I have problems mounting the Taurus radial mounts to a number of planes (Wagstaff Extra/Pitts/Challenger Bipe)-- the best way I find is to mount the engine and mount to some 5/8" ply and cut the bolts off flush with the back of the ply and then mount the plate to the front of the engine box with 2 bolts inside the radial mount going to blind nuts--you can get a ball driver throu the holes in the radial mount. If you perfer, a little epoxy will add piece of mind. (sorry- no digi camera)