Heres what id do. Icecap makes a 4 bulb retro Fit kit, that comes with IC660-09 ballast and 4 bulb end caps and individual reflectors. each bulb will produce around 80ish watts after its overdriven. With T-5 HOs and V-HO's it doesn't really matter what the wattage is, more the spectrum. With the individual reflectors on the bulb, you will get 360 degrees of lighting, so there is much more beneficial light in the tank, rather then deflecting through the glass walls of the tank.
The cost is a bit more up front but with T-5s lasting significantly longer then PC bulbs, you will change them less often, and you also get a better grip of the color of light being emitted. Basically means you have more options on Kelvin ratings then with PCs and you can adjust to get, white, blue or even a pinkish look if you want. You will also use 40% less electricity to drive the same "wattage" per bulb, so you save money in that aspect as well.
with 4 T-5 HO bulbs and reflectors you will be able to keep all low light corals and LPS corals for sure. You may need a bit more lighting for SPS but you could try it and see if it works. I know this is more then you asked for, but explaining everything upfront so you have better knowledge going into it.
Heres a link of the retro kit id recommend getting. Keep in mind you will need to purchase bulbs seperatly, and Id recommend D-D Geismann bulbs, top notch and a very crisp color to them.
http://www.marinedepot.com/ps_ViewI...w~idProduct~IC1535~idCategory~FILTRTRFT5.html
for the lighting unit
http://www.marinedepot.com/ps_Aquar...eisemann_powerchrome_t5_high_output_lamp.html
for the bulbs
Hope this helps and if you have any other questions, just let me know.