Slant 6 coil

1. Are the tachs set up for 6 cyl?
2. Voltages dont seem out of line.
3. Do you have any MSD boxes or the like.
4. Points?
5. Have you contacted the tach manufacturers?
6. You might have black and green reversed ( don't think so but each wires things different)

Tachs only need to see a on off signal from the coil to work.