You can test the polarity of these coils to make sure you have them wired correctly as you can hook them up backwards and the motor will still run, just with weaker spark.
I’ve always hooked mine up with no running issues. Red to ground and black to points.
to find out if Bendix wires are installed correct:
Use only an Analog volt meter to check this polarity:
Put the positive wire to the block and the negative wire to the spark plug wire–turn engine over- it the the
meter moves positive wires are correct.–it the meter moves negative–switch the two wires and test
again.