The reversing gear is different. The lever has notches for forward and reverse and is connected to a rod that passes through the frame of the engine. When you move the lever, the entire brass valve actuator assembly with the gears rotates about 70 degrees.
I have not tried to run them on air yet. It is a little stiff. These engines really were in a barn for who knows how many years. The pictures are after I got some of the racoon shit off them.
Gene