Chris,
Hey bud. Do you happen to have a link to that pump? I was going to try and run the numbers through the headloss calculator here:
http://www.reefcentral.com/calc/hlc2.php
I can't find the pump though. My gut is that you might want the single tube box, especially if your sump is going to be smaller. Over 700 gph through a smaller sump will probably result in some wicked microbubbles. HTH.
Cheers,
- Chad