The A4 was originally designed as an industrial/tractor engine....
This is a common misconception that just won't die. The Atomic 4 was designed from the ground-up as an inboard auxiliary sailboat engine. In fact, the very first engine built by the future Universal was a marine inboard engine. It is true that Universal made engines for many uses other than marine propulsion, pumps and generators and the like, but the Atomic 4 is no more derived from a tractor engine than the current SHO Ford engines are derived from the flatheads. There is an interesting history of the Universal Company at History of the Universal Motor Company 1
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio