Since the basketball represents the size of the Earth with its 23 cm diameter, and the moon is roughly one quarter of the Earth's size, 27% more correctly, the ball that will represent the Moon will be with a diameter of 6 cm.
The distance between the Earth and the Moon is roughly 30 times, 30,17 times to be more precise, the diameter of the Earth, so the two balls, representing the Earth and the Moon will be set at a distance of 694 cm away from each other.
