The OP needs to determine if the '56 engine has the '56 flywheel or a '47-'54 flywheel. That will tell if the starter is 6 or 12 volt.
I prefer a 6 volt starter powered by 12 volts personally. That baby will start up like right now! I drove mine across a parking lot in first gear with the ignition off, with nothing but the stomp pedal to the floor.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission