I have a 120g I am converting in the next couple of months to salt. I intend to make it mixed reef. There will be some sps, at the mid to top levels in the tank and I would like a couple clams. My fiance seems to have fallen in love with acro...which could be a problem if we already have a "mixed" reef

but anyhoo if "things" should happen I want to be able to accomadate that and not have to buy new lighting "if"..ya know?
I have been researching for what seems like forever what lighting to get and changed my mind at least as much as I change my clothes. the tank is 4'long x2'deep x2' wide
Options I was thinking of:
1) Tek fixture 6 or 8 bulb...wonder if I will have enough light for the clam/sps though. Don't know whether to go 6 or 8 bulbs. Less heat and power consumption with this option, but I don;t know anyone else who has sps/clams with a tek on a 2' deep tank....
2) x2 250w lumenarcs and a supplemental light I have lying around (it's a parabolic reflector with some smaller t5's) just to have an actinic cycle during the day.
Please help me decide!