Find a D16Z6 online for 500$, and get a different size head gasket, or pistons... And you got higher or lower compression..
Also, if you swap in a Z6 motor, I am guessing its going to have fewer miles than your motor has. oposed to just swaping the head, you are going to get more out of a total engine swap, for the same price of a head swap..
P.S. Somewhat of a relation to the topic, but, when my head cracked on my H23, it was cheaper to import a motor, and swap the entire motor than to replace the head.