I think both steppers and servos would have their disadvantages, if you had to go for one I would go for the servo.
you could use conventional voltage driver gauges, and drive them from the Arduino , you would then get speed and accuracy, most of the problems with these old sensors and gauges is the senders and the fact that for example petrol in your tank is sloshing around
you could replace temp sensors with digital ones, I would not replace fuel senders.
the Arduino could take these values and average them, better accuracy would be available as you would power the sensors and dials from a regulated supply, and you could calibrate the dials to the output of the Arduino.