overflow is all you need for the display. Then put a pump in the sump and tube it all up and you are ready.
Might want to check out the Durso standpipe as well. I think ebay has decent prices on overflows. You need to try and get one to flow as much as the pump you want to run. I assume with a big tank like that a big mag pump would be needed(9.5, 12 or similar)
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,