On 6/29/2021, Mark Hester wrote:.
"Attached are the Datum points marked in Red but you need a very large reach tool to access them. These four surfaces aren't machined either. Some heads alas don't get skimmed flat.


On 6/29/2021, Dirk Van Ussel wrote:
"This is a 3 mm skimmed head.. Hole is where I tried a plastic hammer".

Highly revommend you do not skim 3-mm off of an MGA Twin Cam cylinder head. While it may work okay on a cast iron head, it leaves the alloy head very thin. Even if it doesn't break, it may flex enough to give problems sealing the head gasket.