ORIGINAL: RCIGN1
UHHHH....You CAN NOT run a CD ignition without grounding the circuit to the engine...The spark comes out of the coil...It jumps the gap..The gap is grounded to the engine through the spark plug threads..It now has to get to the ground in the circuit...If the engine is not grounded to the circuit the spark takes the only other path, the Hall sensor, which IS grounded to the circuit..The Hall sensor will NOT last very long with 20,000 volts going through it....[

This is why my ignition in the mount has no ground wire, it's grounded through the RCA jack scrrewed into the mount....If I just run two wires out of the circuit to the battery without grounding the circuit to the engine the Hall switch dies....Been there, so has TKG and any other ignition manufacturer...The C&H ignitions with the Bosch cap and shielded lead ground through the shielded lead and cap..The other C&H ignitions without the cap have a lug on the end of the braid shield that is bolted to the cylinder or clamped to the base of the spark plug with a hose clamp...You lose the ground, the spark goes through the Hall sensor, the engine stops, PERIOD

Now it someone can figure out a way to insulate the spark plug from the cylinder it would work the other way....NOT possible.....
I'm sorry to disagree with you but it is possible. But it may not be practical.
The coil is a transformer and the secondary can be a complete circuit without being connected to the primary.
The ignition circuit would have the the transformer primary(coil) connected to it and would be completely separate from the engine and the spark plugs. Since the Hall effect device has a magnetic interface it does not have to be connected (grounded)to the engine. Only getting its power from the ignition circuit
I don't know how you would handle the shields though