13.5 volts (average of starting/running voltage) divided by 3.6 ohms = 3.75 amps. You should be OK without a ballast resistor with that coil. The only problem might be during a very hot or very cold start, where starter current load on the battery will drop its terminal voltage down near 9 volts (it happens). That will reduce current flow through the coil primary and result in weak/no spark when you need it most. That's why GM used a low-resistance coil and a resistor in the first place, for reliable starting with low battery voltage, with the resistor bypassed. Keep the engine well-tuned and the battery cable terminals clean, and you should be OK.
Jerry
