Switched 12v source

Then you are arguing the choir. You can NOT tie them together except if you get rid of the factory ignition system. When people make statements like "just tie it to the choke wire" this has to be established. Maybe I should have added "if", "unless"

The OP already stated he is using a RTR distributor, so the factory ignition system is gone
On a stock unmodified harness, run energizes the ancillary circuits/ballast ignition circuit, start energizes the non-ballast ignition circuit
On a stock harness with IGN1 & IGN2 tied together, bypassing the ballast, the ignition circuit sees 12v in both start/run, but does the ancillary circuits also see 12v in both start/run? If that is the case, you can simply use the choke wire as the keyed 12v trigger wire for the Sniper/Fitech.