There are no related tests, but you can find articles comparing FX8300 and i5-4430.
And the comparison between i5-2550k and E3 after overclocking.
E3 is obviously higher than i5, and there is no article that FX8300 can compare with i5. . So for the time being, I think i5 with K is better than FX8300.
Shrinking i5 is equivalent to FX8300.