Yup still using the 70w, seems to do the trick. Obviously it depends if you are going to add co2 or not, but I know people with similar size tanks running T5 strips, 150w halides and 36w Kessil LEDs. Most people make a DIY frame out of curtain rail or similar to hang their lighting from.
About the 70W you are using over the tank, i just remembered that i have made a DIY HQI 70W light that i used over my reef tank. Maybe i just can by a different HQI bulb (6500K) and use my old DIY reef light. Here is some pictures of the light/project: