I would do 2 120's over a tank that width. Cheaper. you wont get all the icky shadowing, Unless you feel the need to do everything digitally? I prefer mine simple... Its the same spread as the 120 i think so if you just do 1 on a tank that large... you're only lighting up half of it.
Except I ordered directly from the company in China, no need to pay the middle man extra.
http://www.ledgrowlights.cn/
http://www.aliexpress.com/store/317880
I have Evergrows Nova a8 over my 36" tank and LOVE it, comapy was great to deal with, they did it up and sent it out super quick. I went DIY with my colour choice as I wanted my blues too be deeper/darker, then what the standard is as well as adding in some red/green, and making my whites more then just 10,000k. Great growth on my monti's and lps, haven't bought any other sps yet. But I have faith these lights will grow anything.