gauge help

[jonesky2]

Rewired my engine harness in my 1970 blazer I see in the new M&H harness there is a wire for the oil pressure sensor.

I currently have idiot lights but im converting over to gauges. I want to know if I can keep the idiot light for the oil and also have a mechanical oil gauge.
maybe a t-fitting?

If not, is the pressure sensor necessary? why would they put a a wire for a oil sensor? I also saw on autozones web site they have sensors for guages or idiot lights so is the pressure sensor necessary for a stock mechanical guage?

I would like to run both if possible but have no idea how to hook up both