I am going to answer my own question
I used a digital multimeter with a frequency counter (marked Hz)
I disconnected the sensor cable at the LH inlet manifold and made up test wires to connect the pins 1 to 1. Then I spliced in 2 x 8' wires between the 2 lower pins and ran these inside the car.
To confirm, you should get about 1.2k ohms between these wires.
OK switch to Hz mode and watch the meter.
The signal should rise and fall with engine speed.
I got approx 6 KHz at 3000 rpm, which equates to 120 pulses/rev.
More importantly the signal did not jump all over the place when the engine was misfiring. Based on this I am assuming the sensor is OK....