RE: Can anyone help with this engine?
You need to communicate what this engine is to get any effective help that is not just speculation. OS is not enough. Going back that far could mean a hugh variety of widely varied types. Picture or two would of tremendous help also any numbers or lettering imprinted on the crankcase. Is this engine a controlline engine or an RC engine (controlline OS engines were far more common in 1964 than RC engines) with a throttle on it?
John