Speedometer Calibration

Tell me anything you about calibrating a Mooneyes Classic speedometer.
It has a cable from the trans to a 2 wire pickup.

 

Think Classic Instruments makes the gauges, etc with Mooneyes logo-ask Mooneyes.

 

I emailed them a while back on the subject and buying a fuel level sending unit,... real incomplete and minimum information. Seems like they are not very customer oriented.