Timing for a 50 hp four stroke yamaha

Can someone please tell me how to time a 50 hp four stroke, unsure of the year- would guess a 2000.

[boats.net]

Timing is not adjustable on a 2000 F50 engine.

50 hp fourstroke timing

This engine has been sitting for years and the valves got gummed up. So I changed the head gasket and had the valves lapped, now I want to put the timing belt on and I am wondering which timing marks to use for firing and do I need to remove the flywheel. The cam is set to #1 top dead center.