For porting the head this is how i understand it. Clean it up is the keep for a basic P&P. The exhauset side you could polish to a mirror for all anyone cars. The Intake should have basically be left to the grinding grit, but knock down the sharp edges and smooth it out so the surface flows constantly. I've seen guy dimple the intake ports to tumble the air, they claim it works.
For N/A Its Go big or go home is basically the option you have, of course this wouldn't stop anyone from doing a mild build of just port matching and be done with it.
For turbo, Enlarge, but be reasonable. You don't want areas to thin to create hot spots.
So If you actually serious, thats some knowlage.
P.S. Don't you dare use a dremel, air tool is the only way to go for this job.