Hello ,my name is Dewey = Dewey's Custom. I have been porting H-D heads since 1978 . ALL the black heads and silver for that matter ,are painted {powered coating} first , completely , before they are machined. ALL HEADS ! The only H-D head that is not painted in the ports ,is the CNC heads. Look in the ports of a 1984 EVO , yes ,the paint will wear away inside the intake port ,now you can see where the air is going ! You never see the paint wore away from 'around' the guide , WHY ? no air there. If you were a little man standing next to the giude {valve stem} ,your hair would not move. If you are worried about it , bead blast the combustion chamber and ports, that is what I always do ,and like what was mentioned ,smooth ex. port and cc , rough intake port {80 grit} but thats not so true anymore { fuel inj.} because your fuel is 'squirted' on the back side of your valve ,and most heads have a great 'squish' so that re-atomizes' your AF mixture ,whatever ,we can talk about this for weeks, don't worry .