Those veglia gauges look the business! Ingenious putting the fuel gauge inside the speedo. Is that the original Z3 needle that i can see?
I believe you can change the direction of the stepper motor on the back of a dashboard gauge by reversing the polarity on the coil. Then, just rotate the stepper motor 90 degrees anti-clockwise on the back of the dial.
More info
here.
All the best.
Chris.