ignition problems hard starting

The ignition circuit for 'start' position is slightly different than for 'run.'
When the the switch is on 'start' power goes to the 2nd Ignition wire - usually brown.
When the key is released and the switch is on 'Run' power goes to the main Ignition wire - usually some blue.

Circuits will look something like this
Circuits will be the same although details will be a different since this is a 67 Barrcuda and you're working on a '66 Fury.
Notice the ignition and the power to the alternator's field circuit come from the same Blue Run wire.

Charging-diagram67B-ALTr3.PNG