History Can someone identify this engine? 1930's 4 cylinder

It's currently on a home made paddle wheel boat. The owner told me it was one of 3 engines like it built. (There's got to be more than 3 i'm thinking...) He said 1930's
Hand crank start and also has a starter and a generator.
Marine engine or some sort? Thank you

 

The blue pump in the back round is a well pump just laying loose on the deck, not attatched to the motor in any way

 

Looks to be a marine engine because they used a reverser box at what is the front of a normal motor, and flywheel now faces the front.

I don't know why the reverser is that large. If it is a reverser, it should be 3 positions; neutral, forward and reverse.

look for br*** parts like carb and any original cooling fittings. Marine engines normally have many br***/bronze parts