A herbie Overflow uses two stand pipes inside your overflow. One is you main drainage pipe and is used to take in water. The second pipe is above the water line in your overflow and is designed to take in air. This allows your main drain to act like a siphon, which allows more water through the standpipe because there is no air taking up space. This eliminates most of the noise associated with draining the water like the gurgling sounds. The second pipe is also there as an emergency drain if your main one backs up. This is the way I set up my tank due to all the advice on this forum, and I have to say Im glad I did. If you google "Herbie Overflow" you should get some answers. Check out ReefCentral (if their search is working) and different threads on Canreef. The tank build journals are great, the link below for fishytimes build is very helpful. Just remember he went with dual corner herbies (Probably similar to what you would want to go with).
Forum topic on Herbies (Mainly a ramble on about Gate vs Ball Valves)
http://www.canreef.com/vbulletin/sho...ghlight=herbie
Fishytimes Tank build Journal. (Pics)
http://www.canreef.com/vbulletin/showthread.php?t=40669
I hate to plug my own build but it might help out as well. I went with a central herbie overflow, but your tank is almost double mine.
http://www.canreef.com/vbulletin/showthread.php?t=52000