TOPIC: '63 40hp Johnson/Evin Lark flywheel installation

I'm fitting a new flywheel on a '63 powerhead. The woodruff key doesn't fit into the crankshaft slot far enough to allow the flywheel to seat on the taper. should I file the sides to let it seat properly? the crankshaft slot is free of any burrs or debris. Also the '66 maintenance manual says to insert the key with the upset mark facing down to avoid having retarded ignition timing. How does the orientation of the key affect ignition timing? Is the original/correct key not symetrical? Is there a change from '63 to '66? Marinengine is calling for the same key. Also the new key has no upset marks, is there another feature to determine correct orientation? Any help will be appreciated, thanks!