Chris,
Since the spark is high voltage low amps any 16-gauge extension cord wire will work. Spark plug wires have a lot of insulation and a noise suppression sleeve to eliminate radio noise in cars, for jet you don't have that problem. Just for safety the crew person should have on cloves to pull the lead off the plug, buzz box should have a push button ON/OFF so the crew doesn't get zapped.
Best, DennisT