The yellow with blue stripe always work for me. You just got to know where to tap into that wire!
Also the negative side of the coil also works.
All my cars I do don't even use the factory igniter and I get perfect signal through the Y/L wire from the tach output on the MSD.
You don't need to hack up your instrument cluster to do that. Where do you think the RPM signal comes from for the tach in the cluster?
Also the add coolant signal is right next to the motor by the PS pump. All you have to do is extend the wire to the coolant level sensor or if you're not using one just ground the wire to deactivate the warning buzzer/light.
Water temp signal, low/medium speeds for the fans and ground for the dash/cluster etc. just to name a few can all be activated through the white and blue plug/connector where the factory harness use to plug into next to the ecu.