Taken from Tomshardware's system builder marathon 1000$ config, Q4 2012. Link:http://www.tomshardware.com/reviews/build-a-pc-overclocking-do-it-yourself,3366-14.html
The system was configured with the FX 8350 and a GTX 670, which uses roughly the same power as the gtx 760.
After an overclock and an unrealistic load on the cpu and gpu simultaneously, peak power consumption was at ~480W.
However, keep in mind that in order to keep power consumption and heat in check, they actually managed to undervolt and overclock the cpu. Even after this, this cpu consumed a full 150W more than the i5 at full load.
This means that if you overclock and overvolt (if you lucky you might undervolt, but don't count on this), know that you should get a decent motherboard with great power circuitry, and a good heatsink.
Regarding the power supply, I would go for 600W made by a decent brand (Seasonic and Corsair would be my first pick) with a 80+ rating (I would go for 80+ gold or higher, but 80+ bronze / silver is still fine).
Get a 600W power supply with 80+ rating and don't cheap out on the motherboard, heatsink and chassis+fans.
550W power supply will probably still work but don't go crazy with your overclock (especially the voltage).