As long as he has decent airflow in his case, he should be able to get a mild overclock on his 440. IMO, the card is not worth spending money on an aftermarket HSF in order to get a higher overclock.
No one can really say whether or not your cousin's card will overclock well or not. Each card is different. With some, you can get crazy overclocks and others may only let you overclock by 5-10mhz over stock, if that.
I would just say to start slow, overclocking first the core by 5mhz increments until you get a hard-lock (during testing) or you start getting graphical errors, and then back down by 5-10mhz. Then do the same for the memory until you start getting artifacts (random white dots that sometimes look like snow, or random glitches like polygonal shapes appearing where they are not supposed to be), then back it down a little.
Of course, if your cousin feels the need for a HSF, it's his money to spend.
My $0.02.