On the Bristol Cars web site it says:
"Bristol Cars have 98% of the original
machine parts drawings from the 1940's on.
If you require a part specially made
to original tolerances,
please ask and we will look into it."
I took this to mean that the parts would be accurate to the original drawings.
But after looking at that head gasket maybe it means if you require a part to original tolerances then it will need to be specially made
If a car manufacturer
knowingly sold me a head gasket that had a cooling hole missing I would be pretty upset.
Bristol themselves could have punched the extra hole required before they sold the gasket - it should not be up to the customer to
discover that there's a hole missing and punch it themselves!