dear Colleagues

This old car has had its head reskimmed following a dislodged valve seat and consequent complete overhaul. A comment was made by the machine shop that perhaps a thicker gasket should be used as over a millimeter had collectively been machined off the face.

What is actually being said> Can a valve hit a piston? If so are thicker gaskets available? Can 2 be used one above the other?
Can a spacer metal gasket be fitted to win back lost meat?

I shall be extremely grateful for some guidance and how to approach this problem, and hope that i don't have to buy a new head since this one now is completely 'new' barring the risky (?) loss of dimension.

Many thanks

Ed