I'd say you labeled it properly.
As for the accuracy.. yeah.. After having my Aeroforce...and you having yours.. think of the temp vs temp gauge and apply that to the oil pressure gauge. It'* a guideline not an accurate instrument of measuring technology like Stan would hang out his window.
I look at it this way..if the gauge is consistent and you know about what the reading is..that is close enough, considering the number of cars produced for years w/o any gauges and only idiot lights.
Or think of it in terms of most Ford cars low and high or cold and hot are the only markings at the outter edges of the gauge with a big "normal" in the middle.
Yup..it'* always normal.