Your motor looks to be 80's or 90's. Not many Mercs of that vintage have traditional woodruff keys. Those Mercs have a "W" shaped where the flywheel and crankshaft mate. The inner flywheel can only go on one way.
Now the outer flywheel can go on 6 or 8 different ways......
1986. You guys hooked me up. I went back and tried to align the rust/stain marks. Worked and both 0 and .464 line up. Flywheel was both put on loose and wrong last time it went for maintenance.
Now I wait for the new puller and holder and will do all the swaps. Will result in a completely new ignition system from key to spark plug.
One day this thing is gonna run right.
Job is a little sentimental since my Dad bought this motor/boat in 86. Got a different thread on the boat. Probably should update it
Thanks for being adamant about the rust/stain.