Um, the Y8 and Z6 cam profiles are exactly the same. The Y8 head is considered better by some because of the size of the combustion chamber and factory quench pads. A $40 head mill on a Z6 head takes that out of the equation. Of course, he'd have to want to do a mini-me for any of this to matter in the slightest. He's just looking for another block to put his A6 head onto.
The Y8 IM is called the D-Series Type R IM.