Help with overflow

[scoobydoo]

I'm about to build and overflow and have the tank drilled. It's a 75g running down 4feet to a 33g or 50g sump. It will have a euro 6-2 and a mag 9.5 for the rtn pump. What size bulkheads should I be putting in. I want to have the corner drilled with a DIY overflow and one rtn on the back.

Any help is appreciated. The contents of the tank will be 80lbs LR, and LPS eventually to go with the fish.

Thanks

[Cheapreef]

I used a 1" on my 75gal, should flow approx 700gph. So it would be a good match for the pump your using.

Clinton