Thats a decent OC for a chip that started at 2.9GHz. I have no idea what scores on AMD overdrive mean, use something representative of the workload you will be doing, why did you feel the need to OC, why do you think you need more CPU power?
If its for games, check your FPS with and without the OC, did it change? If not an upgrade to an i5-3570k will make zero difference whatsoever, if it is for video encoding check the benchmarks for your software see how much of a difference it will make. Increasing CPU power will only improve performance in tasks that are presently CPU limited, if your graphics card is limiting your FPS in games improving the CPU won't do you any good.