Im putt-n together a little motor for fun,

& want to put an ignition [CDI] from a locked up 15 I got some time ago. I heard the taper was the same on the crank but turns out to be 'almost'. The flywheel sits so deep that the nut wont reach it. I got a CDI for an OMC B1 mod that I dont know exactly what its from..

I fit fine & works good. Does anyone know what its from?