Cylinder head milling

Ant said
Just use a thicker head gasket.

If it fits, it sits.

But there may be some logic to it. It's been awhile since I've read anything about cylinder head machining. I need to find my books of automotive knowledge.

Most machine shops have a good idea on what works and what is needed. If they get this kind of stuff wrong, that will not look good for business.

I could not find the book I was looking for, but I got some information from two other books, but one tells you to machine the intake manifold.
I usually just trust the machine shop.