A person can't be totally certain on coil polarity without a coil polarity tester but as a general rule the polarity would be backwards from a negative ground system. Pos+ would connect to the distibutor breaker points and the neg would be the power input from the switch.
The little coil testers are available from most of the resto parts sources but a graphite lead pencil can also be used. Refer to the link from youtube.
https://www.youtube.com/watch?v=9eAHeKDelF0 The spark will jump to the pencil lead then flare a bit to the spark plug. If polarity is off, it will appear to jump from the spark plug to the pencil lead and on to the high tension lead in a reverse polarity.
An old analog volt ohm meter can also be used but not everyone has one of those anymore.