No Spark

The FBO is a completely different box. One or more of the members here hid a GM HEI inside a Mopar box. In essence the same idea. The box looks similar, but the internals are different.

So no, I would not assume the grounded dist. wire is comparable. That is why I was not sure on test results, AGAIN referring to HEI which I'm familiar with, example:

On the Mopar system, "key on" coil NEG should be quite low because the box by default grounds the coil NEG terminal. This pulls current through the coil, and pulls down the coil + voltage through the ballast, making the coil+ voltage "some" low, around 6-8 volts perhaps

A "normal" HEI in the same setup is completely different........with engine stopped and key on, the HEI does NOT conduct. This means the coil is shut off, it means that coil + will be "same as" battery, and that the coil NEG terminal will also be high with battery.

Until the "inventor" of the FBO box comes up with some meaningful information on diagnostics for that system, you cannot assume much of anything