Frank,
pull the back plate but leave the head bolted in place. turn the crank to TDC (top dead center) then pull the head and shims. (if you turn the crank with the head removed there is a good chance you will cause the sleeve to slide in the block and this will affect your first measurement.)
1. Measure from the top of the sleeve to the piston face with the probe on the butt end of the caliper. (write the number down)
2. measure the length of the portion of the head that inserts into the sleeve.(again w/the probe on the butt end of the caliper)
3. measue the thickness of the shim(s)
take your answer from #1 - #2 + #3 = your head clearance (aka. deck height).
hope this helps
chunk