I have a 3hp 1967 model and cleaned out the crud that built up in the cooling system over 40 years causing the motor to run hot. I now have both the head and exhaust gaskets to replace and need some advise. Some guys say to use sealant on the gaskets and some say to install dry. Do I need sealant on the head gasket and on the exhaust gasket? If I need sealant will a local auto parts store have a brand to use or do I go to a marine store? Thanks.......