By this picture:Holy *** that was a long link
It seems that the only fan in the unit is the PSU fan, well placed in front of the CPU. Wow... lol.
Anyway, I don't see an issue as long as the new PSU has the same CFM rating.
Or wait, you mean put a new fan in the PSU. Well, just get one that has the same CFM rating. Or get the best CFM with the highest noise you can stand and find out by changing it. Best way to know something, is to try.