In my experience the position of needles on an instrument doesn't really matter. I operated on a fleet that had a mixture of imperial and metric flight instrumentation. The instruments had different numbers of needles and different Zero positions and rattled through the numbers faster or slower depending on the data. We would fly a metric aircraft in kilometres at metric flight levels and cross seamlessly to a different authority using ICAO flight levels and then fly an imperial aircraft the same route with the same variations.
It doesn't happen now but in the past one could operate different types on a daily basis. I was operating three at one time. There was no problem even though the performances at different stages of flight were markedly different.
Apart from having six base checks in a year.