It's been a while, but I'm rather confident that the 660 maxi's out at four bulbs, regardless of length. The 430 will run 2 bulbs, regardless of length.
My setup was four 48 inch T5's on a 660 and two 48 inch on a 430.
Coralvue still sells IceCap HERE....Chris is the expert on IceCap at Coralvue.