This is the one you want:
http://www.partsforvolvosonline.com/product_info.php?cPath=608_611&products_id=3619
This is the one you want:
http://www.partsforvolvosonline.com/product_info.php?cPath=608_611&products_id=3619
Also in my experience a HG failure tends to be failure around the cylinder sealing ring and not between the oil and waterways (unless the cylinder head has started to corrode which is unlikely, only...