65 Barracuda electronic ignition, orange box, ballast resistor questions

^^This is correct^^ but if it were me I'd go the other direction. There are no current ECU modules that require a 4 pin ballast. I'd obtain the single terminal connectors and to with a 2 terminal ballast. That is one way to deal with it. As said, the protruding pins index the connectors so that the correct resistance is in the correct circuit. The low resistance feeds the coil exactly like a 2 terminal ballast, and the high resistance side went to the (now unused) 5th pin on the ECU connector