boilertrol

While it's winter I decided to renew the cylinder head gasket, timing belt etc. I've had the car six years and did it as a precaution. I'm glad I did, the timing belt was a bit worn, cylinder head gasket was fine, but head was dirty with a couple of burned valves and seats.
Anyway, while the head is off I've cleaned up the ports and chambers, but lookIng at the head it reminded me in some was of my old A series mini. The inlet valves especially are shrouded by the sides of the combustion chamber (see photo).
From measurement there is around 3mm from the edge of the chamber to the cylinder wall. So I was thinking some metal could be removed near the valve to give better flow at low valve lifts. But I've never seen this mod in any of the things I've read about improving k series engines. Is this because there's an obvious problem? Any thoughts on this would be welcome