I just picked up this omc motor today. The serial number is 407208 3. The starter pulley says "outboard motors corp. It is an opposed twin that does not have a magneto. Instead, it has a setup like a Ruddertwin where you need a battery for spark.
.. Please, can you post a picture of the lower unit and also of the backside of the power head with the muffler then I can see if there is a difference between the flywheel magneto or the coil for battery ignition model thanks ..