Take the time to check it with clay. A general figure to allow is .080" for intake valves and .100" for exhaust. If you put the head on without a gasket for checking purposes then just add the compressed figure of the head gasket you are going to use to whatever clearance the clay squeezes to. A head bolt on either side of the cylinder just tightened up snug is enough to do the job here. If you are worried about the clay sticking all over everything coat the valve faces and the top of the piston with either a light coat of motor oil or non stick frying pan spray like Pam. A clay ball about the size of a marble is big enough. From the info you have provided about the pistons, cam and head milling it sounds like you have lots of room but it's still good to know exactly what is going on.
Mike
