Polishing the head does not improve flow, it helps to keep oil residue from sticking to it and allowing carbon build up which can cause detonation.
A windowed piston is for use of a reed vale when the reed is used on a piston port setup, this allows for more intake duration but the flow is all ways limited and metered by the carb size, port matching is making the windows (ports) at the cylinder wall the same size as the carb so that the metered flow through the carb is able to flow into and out of the engine at the same rate.