Just found this info at ebsco auto repair reference center. Maybe it will help? It's been a very long time since I've had to replace an old model switch also.
Ignition Switch and Lock Cylinder
REMOVAL & INSTALLATION
1961-67 Models
1: Disconnect the negative cable from the battery.
2: Turn the ignition key to the accessory position. Slightly depress the pin in the lock face, turn the key counterclockwise, and pull the key and lock cylinder out of the switch assembly. If only the lock cylinder is to be replaced, proceed to Step 9.
3: Press in on the rear of the switch and rotate the switch 1⁄8 turn counterclockwise (as viewed from the terminal end). Remove the bezel, switch and spacer.
4: Remove the nut from the back of the ignition switch. Remove the accessory and gauge feed wires from the accessory terminal of the switch. Pull off the insulated plug from the rear of the switch.
5: If a new ignition switch is to be installed, insert a screwdriver into the lock opening of the ignition switch and turn the slot in the switch to a full counterclockwise position.
6: Connect the insulated plug with wires to the back of the ignition switch. Position the accessory and gauge wires onto the ignition switch stud and install the retaining nut.
7: Position the retainer on the switch with the open face away from the switch.
8: Place the switch and spacer to the switch opening and press the switch toward the instrument panel and install the bezel.
9: If a new lock cylinder is to be installed, insert the key in the cylinder and turn the key to the accessory position. Place the lock and key in the ignition switch, depress the pin slightly, and turn the key counterclockwise. Push the new lock cylinder into the switch. Turn the key to check the lock cylinder operation.
10: Connect the battery cable and check the ignition switch operation.