I understand the concern.
My learning experience about the vagaries of the Z-car oil pressure sending unit happened back in 1974.
I was driving my 1971 240Z home through a snow storm in Spokane, WA and there was already 6 inches of snow on the ground. I looked down and saw that the oil pressure gauge was sitting on zero while I drove. I turned into a parking lot immediately, parked and locked it, and walked nearly a mile through snowdrifts to get home.
I was living very close on income, so I called Jaremko motors in Spokane to see if they had any ideas. They had an outstanding parts guy, and he suggested a new sending unit. I got a ride to the dealership from a friend the next day, went to my car and changed the sender out in about 5 minutes. Fired it up, got a nice oil pressure reading and drove home.
Ever since then, I have taken the readings from the oil pressure system in an L6 Datsun with a certain skepticism.