I'm no expert with highly sensitive electronics or flow machines to confirm that tapering the cylinder helps but I can judge by my common sense that it should flow better when there's no "wall" for incoming air to hit. Small bore Big Block Chevrolets also have this taper from the factory. Yes there is enough material to taper the top of the bore. I don't taper the entire top of the bore just where it's needed where the chambers overhang.
Here's a crude drawing to show what I'm talking about.
