GPZ coil polarity

I have a 1982 GPz750 and I know the IC ignitor box grounds and un-grounds the coils. What I need to know is one if the 2 wires at the primary side of the coils a positive wire? There is a red wire on both coils and the other ones are green and black. I am trying to rig a Koso gauge and I need to plug it into the positive side of the coils. I have plugged the gauge into the stock tach pickup but it doesn't work correctly, I think it's because the signal is negative from the IC ignitor and not positive. Now I am trying to see if I can rig it to a postive wire at the coils. If that doesn't work I am thinking of picking up the tach signal from the pickup coils.

The Red is the Positive.

Like MH said, red is positive, but it is switched positive, so it is always 12v when the ignition switch is turned on. THis is what you would use for power.

The green wire or the black wire can be used as the signal wire for the tach. But you can't use both together without an adapter, so hopefully the tach is designed to use the signal from just one coil.

The green wire and black wire get connected to ground on and off through the igniter. When the igniter is not grounding the black or green wire, that wire is at 12v. So the green wire and black wire each fluctuate from 12v to 0v and back to 12v (which is when the spark happens). The typical way a tach gets signal is by sensing the fluctuation.

The pickup signal on the KZ has a wide range of voltages, both above and below 0v. The pickup signal is also what's called a high-impedance signal. Meaning that it works with very little current. Any outside connection can disrupt the signal and may render the ignition non-functional. If the tach swignal is meant to work from a reluctor signal. it would have to be very high impedance. That is not a typical way for a tach to get signal.