Hy seabeebu3, you can eliminate the polarity reversing switch, they are just one more thing in the igniton circuit to go wrong. If you're going to set your truck up negative ground then the wire from the ignition switch goes to the positive terminal of the coil, after it passes through a ballast resistor, the wire from the negative terminal of the coil goes to the distributor. A twelve volt starter should have an extra terminal on the foot switch, this terminal provides the resistor bypass circuit connection, run a wire from this terminal up to the output terminal of the ballast resistor (the terminal that is connected to the coil positive terminal). That should give you a simple common ignition wiring circuit, from your pictures it looks like you need to purchase the correct twelve volt foot switch with the resistor bypass terminal, and a ballast resistor, hope that helps.
