Roger Halstead wrote:
....
How about the cross sectional area through the intake and exhaust
ports to the valve seats? Are they matched, smooth, and optimized for
flow?

Smoothing the intake and exhaust ports is somewhat controversial. Some say

I don't know much about this, and it looks like John's answer was pretty good. I
have only one thing to add. I read somewhere, probably in a dirt bike magazine
long ago, that intakes should _not_ be highly polished. A slight texture helps
to keep fuel droplets suspended in the air, and not deposited on the walls of
the intake tract. Maybe little bumps in there are like vortex generators,
keeping the flow energized.