Doesn't matter. Easy to figure out by just entering different numbers into tach.Too low and tach reads high. Too many and tach reads low.
Problem you're having is you're connecting wrong wire. Tach & coil signal is NOT +12v pulse like lots of people think. It's grounding pulse. Coils are powered on full-time so you'll measure +12v on both coil terminals. Then igniter momentarily grounds coil to fire plug. So you need to wire up tach for negative grounding signal. Oscilloscope is handy for cases like this.
One pulse per crankshaft revolution.
Put a 10k resistor in the line to condition the signal.
It's actually two per revolution since there's no cam-sensor to determine sequence. End up with wasted-spark arrangement where each cylinder also fires on TDC of exhaust-stroke as well. And its not tap off +12v side of coil or high-voltage secondary. Ground is ground, no conditioning needed as nothing will change.