I have a 44 LED DIY fixture using CREE 3w emitters. I had it over my 58, my 20h (currently while preparing), and my soon to be 40br. With all the LEDs running at 50%, my orange cap monti had no problems growing on the bottom of the tank. LED would be your most efficient option. Another cheap, yet extremely effective opition, would be to buy an electronic 250w mh ballast off of ebay for $100 and a pulsrite 20k bulb for $20. You would need to buy a reflector with the mogul socket (maybe another $100?), but you could grow anything, if placed correctly with just that one bulb (I've done that route to, initially on my 58). LEDs are expensive initially, but in just a couple years will pay for themselves in cost savings of power bill and not overheating the tank (my AC also runs a lot less in the summertime with no MH in the house).
HTH,
Stanley