Not a head gasket, just a water jacket gasket. If corroded, clean up the corrosion and apply something like a Blue RTV to the sealing surfaces and be about your business. Be very careful upon removing the bolts holding the cover in place. It's easy to break the bolts if you aren't careful due to corrosion of the SS bolt to the cast alum housing. Impact is the answer. Since an impact tool is impractical on bolts of that dimension, liberally apply a high quality penetrating oil the night before you work. Get a hammer on the end of the appropriate sized boxed end wrench and tap the wrench till it moves. Once it moves, more penetrating oil and you should be good to go.
On reassy, wire brush the threads and apply blue Locktite as a lubricant, anti-sieze, and thread locker. Torque to spec following the normal cross X pattern used on plates of the sort.
Mark
