On my stock switch in the forty-six, here's what I've got:
Center, top
Armored cable going to the coil.
Driver's side
"Batt" terminal from Ammeter
Passenger's side
"Acc" terminal for devices (turn signal, tachometer, and dash fan are currently hooked here on my truck)
This is the old school stock "two position" (on and off) switch for use with a foot stomper starter.
Might the middle terminal be an independent hookup for the coil wire?
I like Stuart's suggestion of a continuity check. That'll tell you a lot.