I assume you have read the alternator part of the link I posted.
If there are no terminal markings on back of switch, then just test the switch with a light or meter to see how it works. It is basically sending hot to coil when key is rotated CW.
The original hook up: red wire from voltage reg (batt) to one Ignition switch terminal. The other terminal was wired to coil + and to gas gauge. The push button was wired across the solenoid. http://chevy.oldcarmanualproject.com/electrical/wiring/pdf/54truck.pdf
This is all general info. Don't know what all you have done or what components you have. I think you may be running into, the dreaded, PO wiring.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn