First, you should not put more than about 85 GPM over 2" pipe especially if the PB used 2" pipe on the suction lines. in fact in most areas, the velocity limit on spa suction lines is 6 ft/sec which would be only 63 GPM. Over this limit increases the chances of entrapment. You can ignore these safety recommendations if you want to but I would not recommend it.
But the other reason not exceed 8 ft/sec (85 GPM) is head loss. The head loss goes up by the square of the flow rate. So almost any pump is going to be somewhat limited by the 2" plumbing and you are unlikely to get much more flow rate. You need to look at the head curve to determine the flow rate you will get out of a pump. I doubt the Waterway would deliver 240 GPM on your 2" plumbing. That is likely the run-out flow rate (right side of the head curve) which can rarely be achieved especially for an IG spa. But I believe that pump is not self priming so that is a show stopper right there.
Post a link to the specific pump so I can check it out.
BTW, according to this, you need 20-30 GPM per jet. Where did you get 10 GPM from?
Read near the bottom:
Also, the PB should have followed installation instructions:
I would force him to redo his screw up.