You need to, as said, check to see what the switch does. Use a continuity meter to see which terminals are connected to which other terminal when switch is operated. Then you will attach a battery hot wire to one terminal and the switch will turn on (energize) one or more of the other terminals.
The schematic for stock truck and as Dusty says: hot wire from Voltage Regulator "Bat" terminal to ign sw hot terminal. One of the other terminals (the one that gets turned on/off by the hot terminal) goes to gas gauge and to coil. Your testing of switch will tell you what terminal on Ign Sw should be used for hot. Only two terminal were used. If you have a 3 terminal switch, one will be unused. No accessories to turn on, back in the day. Study the original 52 wiring diagram and the kit wiring diagram and meld them to suit. These two diagrams may or may not match wire colors. So wire per function. Exact color is not necessary but nice if possible.
How many positions does your key have? 2 position-Center and right on? or 3 position-center and left and right?
