well pump control box issue
If the control box has one capacitor (a round thing with two wires, usually about 1" to 1-1/2" dia., and 2"-3" long), it'll very likely work. One problem will be that the overload is set for a 1HP motor, and won't protect a 3/4HP. If anything bad happens (like low voltage), the motor will burn up before the overload will trip.
The capacitor is also meant for 1HP, but it'll likely start a 3/4HP.
If the control box has two capacitors or one with 3 leads, it very likely won't work with a 3/4HP motor. This is because the second capacitor is used when the motor is running, not just to start it. Using the wrong run capacitor will cause too much current, and will eventually burn up the motor.