I personally don't think you really need that huge of a pump to drive a beckett. It all depends on the design... Let me explain.
The reaction chamber in my skimmer is about 38" of 6" diameter tube.
The total height of my skimmer is 52" tall. I am only running a T3 (Custom Sea Life) pump which is pressure rated 800gph at 0'. However, by beckett shoots straight down into the reaction chamber with no elbows. I think this makes a huge difference. I don't know if you really have to go with a bigger pump.
Des
PS that skimmate is only 8 hours worth in the cup