If you plan to have A LOT of coral you will probably want more but other than that it should be fine. However, this is coming from someone that's never owned a marine tank and just has done a boatload of research.
I`m kind of thinking you`ll need more lighting. T5HO lights are good but the 120 gallon is too deep IMO for just 4 bulbs. I would consider more lighting If it was me.
I dont think that 4 bulbs will cut it on a tank that deep.
6X 54 watters with individual reflectors would probably be alright as long as your mindful of coral placement.