Everyone seems to subscribe to using the head gasket as the limit to port or relieve to. IMHO this is not exactly correct especially for porting in the combustion chamber. For relieving the bore slightly should be OK for unshrouding, but in the combustion chamber you take it out real close to the gasket which can cause gasket problems. The other issue is the intake mixture hits a small ledge at the top of the bore which will cause some turbulence in a non beneficial manner. I would prefer to Dykem the cylinder head gasket surface and instal the heads on an MT block. Then scribe around the finished bores. This will give a smooth transition from combustion chamber to the cylinder, with only the small area between the difference between the diameter of the gasket fire ring and the bore.
