Starting spark frequency? (ignition issues...)

Here is the deal on the voltage on the NEG side of the coil. First, I am NOT familiar with the "revanator" modules. I know of them, but not familiar
All Mopar "factory like" modules draw coil current with key in "run." This means the coil is switched "on" that is grounded through the module transistor, and will pull the coil NEG low, down to a volt or two

Some ignition modules such as GM HEI do NOT draw current with the key in "run." This means that since the module is NOT grounding the coil NEG, the coil NEG will be "high" or battery voltage.

So what you measured there "may be normal" for some aftermarket specialized modules