Was there every a "correct" connector? I have a stack of old SCSI gear and there are literally 5 different connectors in use. The closest you could get at the time to a standard would be the centronics plug, but I don't think that would even fit on the back of a Mac Plus, at least not without adding expense in the form of a daughterboard or extension cable.
Steve Jobs had left Apple by the time they added SCSI anyway.
Steve Jobs had left Apple by the time they added SCSI anyway.