Emergency kill switch

so, short story, last night, bad crash right in front of our house, welll just feet down the street. We witnessed the whole thing. High speeding crotch rocket hit a Jeep head on, killing that driver and the motorcycle rider was lifelined no word there. VERY high rate of speed from what we witnessed. Anyway, cops stopped by a little bit ago to interview us, they’re trying to rule out mechanical issues such as a stuck throttle(it wasn’t, guy was just being stupid). But now because of that, my wife is freaking and insisting on an emergency kill switch to be mounted on my steering wheel of my Dart since it’s being built as a pro-touring car and gonna have north of 550 hp.

So with all that in mind, I’m thinking of a momentary OFF push button switch, one that when I push it, it interrupts the power from the ignition. Question is, where to make that connection? I’m thinking tapping into the ground on the coil wire. Thoughts?