Like Sam M said about the head gasket. It does not look useable to me. It looks like from the picture that pieces may have flaked off and there are cracks forming in it. There even looks to be a possible crack in the gasket between two lower bolt holes – not sure from picture. I would request a new gasket from where you purchased it or buy another good one. Cylinder head gasket material is completely different than regular gasket paper or cork. It needs to hold the coolant and high compression away from each other and also from leaking internally and externally. Typically, it is not recommended to use a sealant on head gaskets especially a silicone based sealant. People may disagree. I have read that people have used OMC Perfect seal on a head gasket and bolt threads in the past with good results. Best of luck with your projects and you are doing a great service to the students.
