Dunno what car you are working on.

Here are the "good words" from my '72 FSM (I drive a "worthless" '72 Mopar) :

Ballast Resistor Resistance @70-80 degrees F = 0.5 to 0.6 ohms

Current Draw Engine Stopped 3.0 amperes
Current Draw Engine Idling 1.9 amperes

The clerks at the parts stores typically will sell you the 1.2 ohm ballast resistors.

In my opinion, "it depends". I use a .25 ohm resistor with a chrome box. Your mileage may vary.