Hi Tim,
Presumably if they removed the same amount of material from the mating
surface as well as the combustion chamber, it shouldn't change anything
except to move the head inwards by what ever amount was shaved off.
After thinking about my question last night I came to the conclusion
that
because the rockers were pushing on the "open" valves I assumed that
the assembly was too tight but I stupidly did not check clearance
with the
valves closed position. Suds on the brain....
Thanks
Rob