Hi there. Still struggling and clearing missing something important

So far, I've replaced the leads, the coil (with a 12 volt coil), bypassed the ballast resistor, put in a replacement capacitor on the distributor , checked the battery (it's brand new) and still no joy with a spark across the points.

I've used a voltage tester to confirm that power is reaching the coil and validated that the new coil is showing the correct resistance .

I do have a couple of questions or unfounded theories .

1. Perhaps the distributor isn't grounded correctly
2. strange switchI have a strange switch under the dashboard - the only thing I could think of was it was an immobilizer - but I've tried this in both positions (next step is to follow the wiring)
3. Could anyone tell me what this wire does (photo here), it was piggy-backed on the White wire leading to/from the starter ignition switch (I assumed it was related to the choke as it leads to the carburetor


1974 4/4 2 seater