I realize this can be a PITA, and no one I know of has found an "easy" way to calibrate repop stocker senders, either
You might be able to do this by bending/ changing the float arm. Seems to me that if you were to bend the arm so that MT is about 73 ohms, that this should also raise the full setting.
Don't forget, you probably want to put enough fuel in, to drain down to the outlet to establish "true MT" that is, you don't really want the float on the bottom of the tank.
