[snowman]

The folks that do heads probably have no reason not to tell you what material they use or even the mfg, its just that the mfg info is kind of like personal, but not really any kind of secret. The work is routine, again no magic there, everyone does the exact same thing. No special tooling is needed. What is needed is skill, experience and knowledge. You can have the exact same material and tooling as they have and fk it up. The skill level for guides is also on the low end, but guides are not all there is to rebuilding a head, again experience and knowledge comes in handy. Thats what you are paying the big bucks for, not the material.

The material will outlast you as long as its prepared properly. The material being ANY of the ones offered for a Porsche. If there are groves for oil, the valve will ride on OIL and NO wear will happen.

The engine machine shops have nothing to worry about as long as they have the skill and knowledge. THey could even write a book on how to do it and still not affect their business.