JUst use what we used at the Mercedes shop....German torque!Goodentite!
What I would do is not even worry about it,but if you must go buy a whole new set of head bolts,remove and replace them one by one in a scattered pattern.this will keep you from having to worry about the gasket and any mixing of fluids.
Really though after a period of time you cant go back and retorque a set of head (torque to yield)bolts.
