Jim: The Pertronix system will be much better than the original, but if you want to install the points, the black wire goes to the same place as the green one. It will serve as the trigger for the transistor switchbox to ground the coil.
If you only have 6V to the coil, you have a wiring problem somewhere, you must have battery voltage at the coil, the switchbox grounds it, it doesn't supply the power. Note that on the original system (found only on the six cylinder models) the connections were different and power was pulled via the swtichbox. They are not interchangeable. I would personally go back to the Pertronix. Peter
