Homelites BearCat 55's were one of the first four stroke outboards in the 1960's.
This guy in CA (3 hours north of strick in Redding, CA) that refubs them. They are used on lots of house boats and lake boats (lake shasta). The Bearcats actually weigh a LOT less than a 4 stroke of the same HP made today. With those motors . . . I imagine the Johnson + Kirby race boat was more of an advertising piece than a serious competitor.
http://www.4cyclemarine.com/