300 E head gasket
A couple of other thoughts:
Even IF your head GASKET is leaking, you should not automatically draw the conclusion that you need a new CYLINDER HEAD. Do not confuse these two things: a head gasket is only a gasket and costs a little over $100.00.
Check to see if your car actually had a VALVE JOB at 100,000 miles, or just a camshaft replacement. It is not necessary to remove the cylinder head on an M103 motor to replace the camshaft. It concerns me that an engine that supposedly had new valve guides and seals just 35,000 miles ago would burn a quart of oil every 1200 miles.