Timing for T50TRLX 4 stroke

[Haynick1]

Purchased used motor; seller advised it was running rough, seller took it to jackleg mech who advised it had blown head gasket; Mech stripped out several head bolts; mech used helicoils; (1) helicoli did not take; seller refused to pay and picked up motor; Carbs, timing belt currently removed from motor; I want to conduct compression test before sinkin a lot of money in motor; I lined up driven pulley with mark on head; can't see timing mark on driver pulley without removing flywheel; I do not own special tools to remove flywheel; I am confident that flywheel has never been removed: Can I remove the #1 spark plug and rotate flywheel to TDC and then put timing belt on and run compression test without fear of damaging the valves?

[boats.net]

That year model motor is non interference engine but I would remove flywheel and set timing correctly before doing any more to it.