I would call the vendors, some pumps should not go too fast, sometimes they need to stay at a certain rpm where others can go faster, the guys that work on them should know or have it in their books.
With that size electric motor, you might be able to just add another pump to what you have, one pump on the right side side of the motor, one pump on the left side of the motor.
What is the HP rating of the motor at what rpm?