The user manual says you can omit the resistor when using with MSD IGNITION, which is capacitive discharge and works completely different from your Mopar ECU
Your Mopar ECU is "more like" points ignition than anything else, IE the Mopar ECU simply switches the coil in place of the points. Proper coil resistance/ ballast is important with these systems
MSD shows the primary resistance of that thing is only .7 ohms, about half that of a factory Mopar coil