The reason for not putting a mirror polish on an intake port is so the fuel mixture will not strike it and adhere. If the port is slightly bumpy it makes for slight turbulence that keeps the fuel in suspension.
However eliminating sharp edges and unwanted bumps will give up a lot of horsepower. I do it all the time.
Ihave a ported and polished Thunder Tiger GP42 that runs awesome. Of course Ihave never seen a Thunder Tiger GP42 that didnt run good.
Ileave the inside of the liner alone but make some slight mods to the outside. Ever see an Irvine liner? has cuts in it like the RC car guy engines.
I will try to find a photo.