Exactly.....how much space do you have available for a sump to fit inside your stand? I can't make a sump recommendation without knowing what constraints you're working with.
I am breaking down my 55 gallons tank and I have a 27 gallons tall sump, it has 3 divisions, it was made with acrilic separations, LMK if interested and will take pictures. Is your tank set up already or not?