I believe you should be able to correct the problem of the kill switch by simply reversing the wires. . .
On all of the motorbikes i have had, the kill switch works by earthing the positive feed to the coil. I believe the two far poles of the switch are connected to each-other, and to earth. And the centre pole of the switch is the live feed to the coil, which connects to earth when you switch either way.
I would just try swapping the wires the other way.
Maybe it'll help, maybe it won't, but if you never try, then you'll never know.