this is what they told me
to make any cams with more than 9mm of lift physically fit into the cylinder head extra machining is required so the lobes do not foul on the head casting as well as extra time in machining the shims for clearancing as the higher lift cams have a smaller base circle than the lower lift ones.
You are looking at an extra $600NZD for the head machining and $12NZD per shim modification