Huh...
400W for the cards, 150W for the 8350 (overclocked), 50W the motherboard, plus RAM, drives, fans... That should be around 700W... I think you can get away with a 800W-850W PSU. Getting a higher quality, lower wattage PSU is the best choice, if you agree that it would be enough.
I was reading various websites, reviews and even user experiences that they say the cards together can easily want between 600-800W.
Either way, if it is an overkill.. like I say, it's an investment really for any future build I may upgrade to as it should be ample power for a single high end graphics card!