Need help with no spark

If it passes the one-spark test, it has to be either a faulty sensor, or a failure of the sensor to trigger, or a polarity reversed sensor.I have never seen it different.
You can plug in the spare dizzy and hand-crank it to produce a stream of sparks from a near-grounded coil wire. The key needs to be on, engine not running. The dizzy does not need to be grounded. This is a lotta fun. zzzzzzzt,zzzzzzzzzzt,zzzz zzzz zzzzzzzzzt,zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzt

You can set the initial timing with polarity reversed, but 1) the timing will not be where you expected it to be,on start-up, and 2) the engine will not take throttle, more than a couple of hundred rpm. If you watch the timing marks at this time, you will see why. It will be jumping all around, even retarding, and completely skipping some sparks.It will, however, idle pretty good.