I'm not saying it won't handle it, i'm saying it's pushing it and there won't be much headroom. the 600w psu that he's picked is fine.
Also, if you ran SLi 470's on a 550w PSU it'll kill the PSU very quickly, Phaedrus recommends a 750w PSU for SLi 470's...
I recommend a good 850w for that.
But the fact I can run Furmark at the clocks mentioned with the 550w Kingwin with two GTX480s tells me the 500w is perfectly fine for one GTX470 no problem.