You will gain very little performance, the performance of each core on the Vishera line is very low, and the two extra cores will provide maybe a 15% increase in performance at most.
You'd be much better off buying a cheap aftermarket cooler like the Raijintek Aidos, the CM Hyper 212 Evo or the Cryorig H7 and overclocking your current processor to as high as it will go. I believe that with this level of cooler, the FX-6350 will hit 4.5GHz, maybe more.
Woody