you most certanly can its not a overall HP gain but it will give you a notciable power ban increase its all in the way the head was made as in the Y8 tends to circulate the A/F around oposed to just dumpin it in like the stock z6 head i have been wanting to change my D16z6 head for the Y8 for some time now but I lack the funds and the time to do it.....but if you have the opertunity to I would as well as change out the rods and pistons you can use the rods out of the ZC and the pistions from a 90-91 teg for better comprestion and androds for better hp handling
I hope this helps you out a little
art