Looking for bigger HOB Overflow box

[jaxteller007]

So currently we have a CPR CS90 on our 75G tank. It's rated at a maximum of 600 GPH (I think that's actually lower than the minimum our Sicca 4.0 return is rated at). I've been told by a few people that we should/need to go with a larger overflow box so I'm hoping I can find a good used on on here. New ones are just too dang expensive right now when ours is "working".