Did a quick sketch of the tank. It's not even remotely to scale, but here's how the drains/overflows, returns are going to work.
Two overflow boxes on either side of the tank, each with two holes. The left side is directly above the return pump in the cabinet, so the holes will be a drain and the return. The right side will just be a drain and an emergency drain.
The return will come up above the overflow box and run over the centre of the tank. Since my canopy is completely enclosed and I'm likely going with modular LED lighting, the centre return line shouldn't (I hope) interfere with the lighting. This design also reduces the number of holes I need in my tank and thus the size of the overflow boxes, and it gives me the ability to distribute flow towards the centre of the tank, or to specific dead spots that the vortech's might create.
I will also need 2 return drains and an emergency drain to become completely blocked before I have a flood.
Not sure if I should go with 4 MP40's or 2 MP40's and 2 MP60's though, anyone have any thoughts?