gas columbia par car ignition switch replacement

[blacklion]

I have a gas columbia par car Vin # 2L-20881-DL, and I would like to get rid of the faulty key type ignition switch and replace it with just a 2 way button type switch, has any1 got any wiring diagrams? the switch has 4 thick black wires and 3 thin wires and 2 of them are joined with a diode, Im in Australia and it's hard to find any1 here who knows much about these things let alone change anything from standard. Cheers