When an engine overheats severely smoking heavily due to plastic bags, banana peels blocking side water intakes you must torque back head gasket to specs, if doesn't better, replace for a new one, but before doing so, check head with a metal ruler to be completely straight and even border to border, as you already could have a warped head product of the overheat. When replacing new gasket won't achieve a perfect chamber seal between crankcase and head walls. Take advantage to clean all internal engine water passages.
It's always a must visually check at all times water peeing through small lateral hole located at right side of engine if boating in kelpie, contaminated seas. If you drive sitting opposite peeing hole, you will never see engine peeing and that's overheat candidate to ruin your boating day.