how will they be oriented?
what are you using for reflectors?
which SHOs, straight bulbed or spiral bulbed?
what spectrum/color/etc.?
2wpg in clamp lamps hanging 6-12" above your tank will likely put you at or near high light with decent bulbs.
with the same bulbs in a retrofitted all glass t-8 hood with white plastic reflectors, sitting directly on top of the tank you'll be getting low light most likely.
They are spiral 23W daylight bulbs i got from home depot. Either 6400 or 6500K. Plain white reflector. I attached a rough sketch of how there oriented for now. I plan on building a wood housing for them that will be better but this is to get me started. The red squares are the bulbs, one exception being they are all centered