My 64 has a sbc 350 in it and I'm pretty sure the oil pressure switch has never been connected.
I am not running gauges, just the light in the instrument panel.
My question is;
Should I place a pressure switch in the position behind the carburetor (currently nothing there) or the one near the oil filter (which as yet I can't see; only had a quick look today)?
And I'm guessing when using just the instrument panel light I only need the single prong switch?
Idiot light uses single prong sending unit. You need a gauge and a matching sending unit to get an electrical gauge to work. In the Camaro, Nova, and Chevelle the oil pressure gauge is mechanical, not electric. No knowledge as to full size cars, as factory gauges are very rare.
Pascals law states all hydraulic pressure is the same every where in a closed system so it doesn't matter where it is measured from. In the old days I used the front of the block location as it was the furthest from the pump. If I had pressure there I had pressure every where else in the engine.