I wonder if that small tab is it and if a 1/4" (female) spade connector will slip over it. If you try that and it works, well there's your answer.
So, a short length of wire, connected to that small tab, engine running and apply the other end of the wire to anything metal on the engine.
If it dies, there's your dinner.
One thing is certain, that coil is old and looks to be one of the crossover ones when Briggs modified(?) existing stocks of ignition coils to work with the older flywheels(?).
I've seen one like that before with that extra plastic incased pickup nestled between one of the "legs" and the central coil. . . .