I rebuilt a '82 Spectre 750 motor, it has the same holes.
Since mine motor is a Canadian spec unit it came without the pollution equipment, so I did not think to tap and install a plug of some sort - bad idea! It leaked on one side of the cam cover really badly. Since the head was already on a fresh rebuild I decided not to mess with any tapping (would be just my luck to get shite in the motor) so I opted to cut a new cam cover gasket and around that plug hole I put some RTV on both sides of the gasket paper which formed a very good seal. This fixed my massive air leak which made it run shitty.
If the head ever comes off again I will tap those holes for sure!