i would go with a 55g and a lifereef overflow.
Any overflow with a 1 inch pipe will have a max flow rate of 700gph. You would not really want to try and achieve the maximum, ....unless you want wet floors.
I would suggest running around 500gph through the overflow. Separate the sump into three compartments, one for water entering the sump (I keep a lot of liverock there to stop bubbles). the middle chamber is where I sit the return pump. The other chamber is the refugium....here I have 5-8 inch sand and chaetomorpha. The refugium is fed by a "T" off of the return pump so I can control the flow.
P.