Pertronix III set up

Ignitor III should have its own dwell control IIRC.

How reliable is it. I don't know.

My suggestion is this. Go buy a half dozen piggy backs terminals.
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Use them to jumper the Ignition J2A & J3 wires together at the ballast.
J2A is ignition 'Run' power and J3 is ignition start power.
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Another way to jumper them is two 1/4" wide male terminals. Then insulate and zip tie them so they don't move and chafe around and don't ground.

Then you can go back easily if it dies.