pepper'scove

I have been looking pretty heavily at making my own lighting for a new 75 gallon tank I just got. I'm debating whether to make an LED fixture or use MH lamps. I am wondering what the light output need would be for a standard sized 75 gallon (I realize LED and MH are different so whichever you guys know more about, please fill me in!). I would like to ensure that I can care for SPS corals adequately (the tank is 21" deep). Also, I am planning on hanging them 6 - 8 inches above the tank if I do MH, unless you guys think differently, and I'm thinking maybe 3-4 inches for an LED light. Suggestions!

Specifically I would like wattage and spectrum suggestions as well as suggestions on combination with flourescents for MH. For LEDs just throw everything you have at me.

I will be building a canopy to go over the tank (I built the stand, finished except for trimming it, and someday when I'm not so lazy I'll do a write up on that with LOTS of pictures, diagrams, 3D models, even a cut list!!) so height doesn't have any limitations and width and length are only limited by the dimensions of the tank - 48" long by 18" wide.

I appreciate everyone's input!