I second the recommendation of the 1262. It puts out a lot more flow that the specs would indicate, just use a 1 inch flex hose to feed it.
Running giant return pumps is old school, and it costs you a ton of money to pump all that water uphill, as well as potentially a lot of heat in your tank. Save yourself some $$ on your electric bill and put in 1 or 2 Tunze Streams, or the upcoming Ecotec Vortec pumps from Icecap (or a closed loop, but that's another thread all together). You should shoot for about 5x your water volume through your sump to help keep detrius suspended so it can be skimmed out, which the 1262 will do nicely.
LOL, I just realized this is the third thread I've posted about the 1262. I'm not affiliated with Eheim in any way, yadda yadda.