You have to come to terms with modification of a "Rare" Cylinder Head. Should you return the Guides back to stock? How can you do that? It is possible. It is not hard and not many people realize actually how simple it is to grow more metal on the inside of a valve guide. You do not even have to water the guide boss. Of course it does take some time and it will then have to be machined back to the original dimension of .343.8 inches, plus or minus .002 thousandths
