I dont think you have to be worried about K7 on the turn. Im way more worried about a set but i doubt he has one when he goes allin. If he is a wild player (or one who will call you with overcards and then go allin when he hits his K) then you should probably call. It comes down to what you know about him. Does he bet strong with good hands? or with rubbish hands? or does he bet strong with any hands? Thats the question you need to answer.
With no read other than "wild player" i think you have to call here.

edit: Actually im talking more from a cash game perspective. In a tournament where survival is more important i *might* lay this down. It depends just how wild he has been playing.