Ah yes, I see that now, I skimmed the thread a bit too fast. The CFLs will work fine if you want to keep them for a while until you build the LED array. I would replace the lamp though and for that size screen/tank I would use a couple in the 23W to 36W range with large (10") reflectors.
If your goal is to support a mandarin dragonet, don't count on the screen to provide these in enough quantity until the tank has matured - IMO, 6 months or so under moderate bioload and algae growing well on the screen.
Like I said, you can under-light the screen and still get the filtration level you want. So there is not an absolute need to take it all apart just to reduce the screen size, just realize that the screen is oversized and this may cause the growth to spread out and not get thick. You will probably still get adequate and effective filtration, but you might see some weird patches of growth like yellow spongey stuff, and dark growth at the edges, but you will definitely have an area of green growth also. Oversized isn't the worst thing, it's just on the inefficient side, meaning it has a longer slot, more water flow required, takes up more space, etc...I would just go with what you have and see how ti goes.
Also have you asked the seller how much growth the screen got, how much he fed, how often he cleaned, etc?