It depends on the coil and to a lesser degree the amplifier.
Original systems in '73 used 0.5 Ohm to the coil. see 1973 Chrysler Electronic Ignition Diagnosis and Repair, the Master Technician Service Conference (Session 312)
Direct Connection gave 0.5 Ohms as acceptable for coil with all Chrysler units with some exceptions noted.
Those exceptions include the Accel Super Coil (.8 Ohms), coil 5206436 (.7 Ohms) and for racing with certain ECU's, coil P2444641 with .25 Ohms resistor. fig. 19-3 &19-6 p. 367-8 Mopar Engine Book p4349340
