You mentioned wires reversed on your kill switch. Normally a magneto only uses a single wire on the switch, with the switch grounding that wire through the switch body to kill the fire. Do you by chance have an external coil on the magneto? Did one of the wires on the switch go to a ground? As Raymond stated, you can use a 2 wire switch for a kill switch, but one side has to go to ground, and as Raymond stated, it will work backwards.
If you are not part of the solution,
you are part of the problem!!!