that would really mess up compression ratio and even cam timing. The head shaving was the end of the life for this head, it was not even needed unless the head was warped, if the head galleries were corroded they could have been built up with aluminium impregnated devcon epoxy and shaved with a blade then the head gasket sprayed or coated with hylomar and tightened to correct torque.
(source: I owned an 808 as a teen, fixed it on a shoe string budget and then swapped this very same engine in it as a no charge swap from a taxi owner who was using this same model car as a taxi in Karachi)
hylomar + devcon build up works sweet.
btw this engine is the same that was used in the 1974~75 mazda 929. It is (H)