If you are willing to overclock then get the 7850. It's a solid card at 1000mhz on the core, a basically guaranteed overclock on the card.
The 650ti boost 2gb is a good alternative, but taking into consideration the overclocks the 7850 does it's the best of your options for performance.
430w quality PSU is fine for the 7850. It consumes ~130watts, there's plenty of power on a 430w for the rest of your system.
i3 4330 | Sapphire 290X Tri-X OC | 240GB mSATA | 550w XTR | Lian Li HTPC Case | 54" Plasma | 5.0 Paradigm Sound
A wise man changes his mind, a fool never will. - Spanish Proverb