1/8" NPT to AN3. Most tracks only prohibit fuel being plumbed inside the car. I am running Kevlar lined brake hose. Good to 2000psi+ and 500°+. If it fails while being used to feed an oil pressure gauge, I've got bigger problems than the gauge.
I don't trust electrical gauges. They are too slow to respond in my experience and since most of the affordable ones are 90° sweep, they don't give accurate information. A gauge that isn't timely or accurate qualifies as a fancy looking idiot light in my book.
Rich aka Dr. Bilkenstein, the three footed hobbit
Rally Revolution #21