Boy . . . . I gotta say as cool as all that gear-drive is (who's?

), it would seem like with all of that inertia of turning gears coupled with the hammering effect, that perhaps with a few good "throttle-snaps", or some brutal gear changes (with a tight clutch), and the camshaft gear retaining fastener & key would just maybe surrender?

Looks like a good application for a "splined" juncture between the drive gear(s) and the nose of the camshaft stub.

Scott.