Nice find and good luck with it. I've been thinking of going back to T5 for my 180. I would jump on that 60" 8 bulb if I though it would cover the whole 6' tank. but im not sure the 6" short on either side would make a difference.
how the weight of the fixture feel like?
on the heavier side or lighter side?
John, once centered over the tank the 6" on either side wouldnt matter... and the lower par on those sides would make it great for accilmating corals and any softies/lps, chalices you want to keep....