Valve to piston clearance

If there is enough meat on the piston, the valve relief can be made deeper. I'm not to familiar with big blocks but if you have 1.6 rockers go with a 1.5 ratio. Another option is to change the cam for something with less lift. Sink the valve seats in the head, but I don't think that helps flow any. I don't think a thicker head gasket is going to get you safe clearance without doing something else.