yes, but not 1, you will need two 150wers, 150w MH's only have a light span of 2 feet, 55g's are 4 feet.
you should not go by the WTG ratio, you should go by intensity or PAR.
There are many other factors to keeping SPS then just light, and IMO lighting si the most flexale, SPS need very mature tanks, correct water paraments, and stable water paraments. also flow, SPS love flow!, it is recomended that you have at least 30X turn over. in a 55 gallon i would get two 1100 Rio Seio's and have one on each side of the tank, and maybe 2-3 maxijets in the back to keep deterius susspened.
Now skimming, with sps you need the biggest, most baddest skimmer you can get! with a 55 try to get an ASm skimmer, a good model is ASM g-2 or ASM g-3, get the tallest most expensive and most gallon rated ASM skimmer you can afford! dont skimp on your skimmer! ASM are same as Euro reef no matter what people say.
so just check that your:
Water Quality
Flow
Filtration
BIoload
is all in the proper ranges for sps.