leaking head gasket

[bwagstf]

I just replaced a head gasket on a 1982 15 hp and the gasket is leaking. This all started with a cross-threaded spark plug. When I removed the head a head bolt broke and after drilling it out and re-threading the head bolt I thought it would all go back together. Water oozes out and the engine is running on one cylinder. When I rev it up, in gear, it runs on both cylinders. The engine was used extensively in salt water and corrosion seems to be a problem. Any thoughts on using two head gaskets?

[boats.net]

You might take the head to a machine shop and have them mill it and clean up.