Spun dampener

If it's a marine engine,, a lot of them had the timing mark on the flywheel cuz of all the pumps and stuff up front..

You're gonna have to watch the valves timing, and rotate the crank,, to see if its a reverse cam, that can be changed..

The notches for the rear main seal, if wrong, can be polished out,, I've seen many..

And as for starters,, some just reverse the starter and drive rotational direction..