This little screw has been a PITA since day one. Soft as the dickens, lousy. So you can see it's easy to find an M4x.7 screw with the same length. But alas, it must be chucked up (the drill works fine) spun and ground on a grinder (or other - file, grind stone, moto tool, emery cloth) until the head diameter is the same as the cutouts in the flower nut.
Then some careful material removal on the thread face - because if you don't do this the screw head will hit the clutch cover.
Done. Now adjusting the clutch if fun with the SBP cover mod.
I know its an old thread but I wanted to add to it,,I was always thinking this little locking screw may be a weak link in the kit,,after the new better quality bolt is installed(allen head preferably) i would place some nail polish on each side of the bolt to help it stay in place,,if need be removed the nail polish will crack right off not like loctite that would be a recipe for another stripped head