You certainly can OC and there is certainly nothing scary about overclocking with BCLK, back with Intel 9xx it was the only way to overclock. But as I said above ... it is limited with most reporting from 3 - 5% and some as high as 7%....and it requires that your other components be able to handle that BCLK speed.
Then again, when ya look at it from the perspective that the $100 difference between a 3570k and 3770k nets you under 3% it kinda seems less significant....with the very best of luck, it's kind a like getting an OC of 4.2 Ghz on a 3570k by using the CPU multiplier.
Personally that's why I don't bother with H series or B series MoBos but if ya stuck with one, and budget doesn't allow a new MoBo, I'd certainly have no issue attempting 5%.
If you do have the budget, I'd drop any consideration of the 3570k or the H61 and Id grab:
$135 solution
Intel Pentium G3258 (Haswell)
Motherboard MSI H81M-P33
$350 solution
MSI Z97 G45
Intel 4690k