I would suggest you take a look at Hoppy's sticky, which is posted at the top of these forums.
Thats what i was afraid of.The light with probably only give you low light if it even does that well. Most of the older fixtures for 65 watt PC bulbs had poor reflectors, and without very good quality reflectors they didn't produce much light. Even if the fixture uses AH Supply quality reflectors you would only get low to low medium light at best.
Good points, ill go with the 4x2The two good reasons for using the 4 foot fixture are:
It matches the tank length.
Four foot bulbs are much easier to find in the color temperatures you will want.