Agreed, a replacement powerhead. The early 1956 30hp motors had the troublesome 303804 lower seal, which was continued from the late 1955 25hp motors. Lots of powerheads got replaced because of that seal letting water into the crankcase.

I found out about that aluminum inner exhaust cover the hard way. That was an expensive come-back job. You can spot the aluminum cover easily. It is thicker. The stainless steel ones are only about as thick as a credit card.