I agree with B1 MAX. You really should do a careful clay check with 1 cylinder outfitted with the actual valve springs and valve gear being used or considered. The system of checking with a dial indicater only checks the depths of the valve pockets. It doesn't check the valve margin's radial clearance in the valve pocket unless it is the first point of contact when checking the depth. You could have only .002" radial clearance and never know it til you fire it up and that ain't gonna be good. When I had the pistons made by Diamond I told them they were for Victor heads, they said it mattered as they were somewhat different than others. I ended up with plenty of clearance there when I assembled. Careful clay measuring is quite accurate contrary to what some believe.It is the only way I know of to see actual verifiable minimum radial clearance. I'm sure that statement will draw a lot of fire, but I'm speaking of a proceedure we could all do in our driveway or garage and feel safe with our findings. Bill