Paul,
Just make sure that you use the proper resistor with that new Black coil. The coil should have a label on it which states the resistor to use. Your tii is probably using a 1.8 ohm resistor. You can check on the resistor to see if it is marked 1,8 on it's metal base. Some black coils require a 0.9 ohm resistor. If that's the case, you might have to swap your resistor for a 0.9 ohm one.
If you're running a Petronix, you want to hook up the positive wire of the Pertronix unit before the ballast resistor so that the Petronix gets full 12+ voltage.
Good luck,
John