Sorry, but I don't track this thread all the time.
We have been remanufacturing cylinder heads, blocks, mostly custom work with performance upgrades in mind... Lots of porting work, upgrade cams, our Molnar rods are the only ones that we know of that are 4340 CrNIMo material for strength above and beyond... and we continue build from mild to wild.
Glacier9, your questions are much too in depth to cover briefly. But quite simply the difference in a 1Z and an AHU are the diameter of the valve stem 1Z= 8mm, AHU= 7mm. Sorry to have undoubtably missed your time element. When we recondition a cylinder head, we leave nothing to chance. Everything gets touched, we always install our custom guides, We always recut the seats, we always seat the valves and get the correct valve projection. Then, we do a lot of things that you may not see, but improve the cylinder head's life expectancy and reliability.
Removal of material to satisfy head gasket surface requirements is NOT the dimension we use. The projection of the exhaust valves and how far the seats have recessed determines the amount of material removed from the head gasket surface. The valves must project below the head gasket surface the correct amount. Then, the valve stems are trimmed to keep from over-compressing the cam followers. There are no step you can 'skip'.
AlanZ,
When it is a question, we do dye-check for cracks. The damage is usually visible, so the use of dye check is not often necessary. The most common crack is between the injector bore and the intake seat. When we see that, our recommendation is to not use that cylinder head for performance work.
There are other places the head will crack and the use of dyes does not reveal them. The other relatively uncommon crack we find is specifically in the #4 cylinder's exhaust for the ALH. There is an issue with the mold mark having porosity from gas bubbles trapped in the pour. This damage requires pressurizing the cylinder and looking for bubbles. Even then, cracks into the water jacket are tricky. The method for finding hairline fractures is about the only time we find the value of using WD-40, as it will make a very small crack stand out. A mist of the penetrating oil will rise from the water.