[Mach 1]

I guess I can see how the clay would help determine port misalignment, but how do you enlarge the lower port to the gasket size at the same place it needs to be enlarged when it is sitting on the engine heads? Just holding the gasket on the lower will show you how much smaller the port is, but how do you put the gasket on the lower in exactly the same spot it will be in when bolted to the head?