I wouldn't try to remove too much material. If u over do it, you can really screw it up and it can't be returned to the way it was. I'd focus on cleaning flaws and smoothing/blending everything, sharpen the transfer ports and the bridge on the intake and raise the roof on the exhaust. The reason you don't want to polish the intake is that the fuel will tend to bead up on the high polished finish and won't get broken down properly. A slightly rough surface will cause the fuel to break up and get sucked into the intake the way it should. Nice even dispersion. The exhaust on the other hand is just a gas that you want to exit asap that's why the smoother you get it the quicker you get it out. As for the piston, it's not necessary, but you can open the windows and it will make a slight difference. What your trying to accomplish is to get the piston windows to match your port windows. Going bigger than your port windows won't do anything except weaken the piston. Also anywhere you grind on the piston or the sleeve make sure to get everybit of burr off(use a magnifying glass if you have to). You don't want anything catching a ring or scoring your cylinder.