So what are the specs on your 3500 heads? I don't install them (don't install any mini-rotor heads)
Here is another worthy line of jet pumps, the JS series by Goulds. I include this, because I don't see the equivalent info on the Myers website. You may find that a
good 1/2 HP jet pump will work after all. Understand, though, that you can't fudge the numbers, and also understand that any pressure losses in the suction pipe plumbing have to be converted to additional suction lift.