would 384W of PC lighting be enough?

Would 384W of Power Compact lighting (4 X 96W) be enough for nearly "4wpg"
in a 77 gallon tank? (48"x24"x16"). We have about 2 feet of height that this
light has to penetrate strongly. I'm pricing out some retrofit kits that go
from 220watts (4X55) to 440watts (8X55W). I realize that PC lighting is much
more efficient than the more conventional T8 or T12...but I don't know how
it rates in the watts-per-gallon scale. I was thinking of metal halide but
don't like the costs or heat factors.

Thanx for any tips and ideas!!



Dave.