Disclaimer: I have no experience overclocking Haswell, the following comments are extrapolated from my knowledge of IVB overclocking.
I see little reason to go with the "K" version of the i7. With IVB (and probably sandy) you could raise the max turbo multiplier by 4 using a Z77 motherboard.
So right there, the 4770 could max-turbo up to 4.3GHz. With Haswell, Intel has allowed for Base Clock Speed straping. Considering TR's report on Asus' overclocking findings,
most chips should do 166MHz base clock (100MHz default). Frequency is Base Clock x Multiplier = 166MHz x (39+4) = 7.13GHz.
Now, obviously you're not going to hit 7.13GHz without some pretty serious cooling (LN2), and not having an unlocked multiplier will force you to be more creative with the multipler and BCLK, but here are some examples. (from 100MHz base clock and 39x max-turbo multiplier as default on the i7-4770)
100MHz x (39+4) = 4.3GHz - Should be accomplishable on most air coolers at stock voltage.
125MHz x 39 = 4.875GHz - Probably going to require a 240MM water cooler.
IIRC, you can lower
the max-turbo multiplier as well to achieve results between those two.Read here for explanation of TSX
i5-3570K, ASRock Z77 Pro4-m, Asus GTX660 TOP, 120 GB Vertex 3 Max IOPS, 2 TB Samsung EcoGreen F4, 8GB G-Skill @1.25V, Silverstone PS07B