I presume you mean 4770k or 4790k as they are the only k series i7's? You don't have to spend a fortune on a motherboard for a decent overclock anymore with Haswell. A board around £100 will do most of what a much more expensive board will do and unless using extreme voltages and cooling such as LN2 will overclock more or less the same. You don't say what form factor you require so assuming ATX my recommendation would be the
Asus Z97 Pro Gamer as it has a very good balance of features against price.