Mrclubike, now that makes sense. I know that the negatives are the brown wires grounded. But didn't think that negative wire on the coil changes +-+-!! Thanks for that.

Yes so I got that black wire from the coil connected to the RPM wire of the gauge. Managed it to work but comes on and off intermittently. Grounding? Gauge fault? I hope I haven't buggered the gauge yet.
Got those blue exciter (D+) connected properly, charging is good. I had that resistor tapped in as well.