@ ItsSoLARGE: I was thinking of a shroud, but I can't figure out a design that would work. Normally, you have a fan smaller than the radiator, but in this case it is reversed.
@ jtroutma: Do you know of a place that carries 10" chrome grills?!
@ jaydee: I thought the res would be a good idea for filling. Also, it would collect any air bubbles. I don't really think airflow through the rad would be inhibited too much, because the res is about 1.5" from the rad. Also, even on the lowest of the three settings, the fan still pushes quite a lot of air. 550 CFM at max, perhaps 200 on low. So optimal airflow is not much of a concern.