Squareback vs round back alternator?
The triangular connector is a way to identify the 1970-1976 voltage regulator that controls the field ground with an isolated field alternator.
Electrons flow that way (toward high voltage). In common conversation we usually describe current flow the opposite way. So I will write that current from battery (12.5 Volts) or Alternator (14 Volts) flows through power wire (J-1) into key switch. from Key switch out the ignition terminal to the junction on the ballast resistor. At the juntion, current divides. Some flows to the voltage regulator and some flows through the resistor to the coil, then through the distributor points to ground.