Gauges Quality

[PxTx]

Sounds like you'll have a lot going on. Tyically the Greenline tach require a sending box. I've only seen them go as high as 9k, but maybe there is a 10K.

In that situation using a modified ZL1 I would probably recommend sending the tach out to be "updated" with modern electronics and checked for accuracy. This way you don't have to worry about how some sort of multiple spark and/or CD ignition will affect the tach.

The Sun tachs were one of the most accurate tachs of the time, but Rosen did make comments that some CD ignition systems were less compatible with some tachs and that is why he used the GM hood tach on a few.