If you are planning on overclocking, you will want a Z77 based motherboard. It need not be a high priced enthusiast version. M-ATX will usually be cheaper and will be just as good so long as you are using a single graphics card(which I recommend) What you might do is buy a 3570K first, recognizing that your H61 motherboard will allow you negligible overclocking. Then, you might find out that the 3570K is strong enough at stock to do the job and save yourself the expense of changing motherboards.
But... if you want to change both your cpu and motherboard, then consider a Z87 motherboard and a haswell 4670K.
The performance will be similar, but you will be on a current 1150 socket, and be prepared for broadwell 16nm.
In the mean time, the X87 motherboards have some nice upgrades over Z77.