I understand that if you hold a wooden pencil's lead point between plug wire and ground - with an air gap both sides - you'll get an indication as to proper coil polarity.

If the visible spark is on the plug wire side, polarity is reversed.

If the visible spark is on the ground side, polarity is correct.

A further indicator of correct polarity is if your spark plugs don't seem to last long - maybe 1500-2000 miles at most.
Assuming of course, the engine is in correct tune.

Correct polarity should have your plugs lasting the usual 10,000 miles between points ignition tune-ups.