Re: old montgomery ward seaking
Most of the early Monky SeaKings were made by OMC's Gale Products Division. They didn't have a 6 HP in the line, but if its a 5 HP its probably one of them. Parts should be as easy as any OMC.
In later years, they were made by West Bend, and they did have a 6 HP model. 1958 or 1959. At that HP it should be water cooled. I don't think common parts like ignition and spark plugs would be a problem.