Just got power back on, been out with a wind storm.
I don't think it's going to be possible to see the gains of polishing or not on the ports. The difference between any two cuts in a log is going to be greater than the % gain/loss from such subtle changes. Need to trust technical reasoning and studies done by others working bigger motors on dynos ect.
Overall if you want a fast saw you can't start discounting small gains here and there.
Likely more important than polished smooth is getting the walls flat, getting all the humps and bumps out makes a significant difference to flow. A good smooth exhaust port helps keep the carbon off.
A polished aluminium surface might not do as well at blocking heat where exposed to direct flame as one would think. I did a little testing on heating aluminium finished in different ways with a dirrect flame. The aluminium sample that failed first was the pollished one, well before the dirty oxidized aluminium. I'm suspecting this is due to a reduced boundry layer held near the surface by surface texture and also the lack of a protective aluminium oxide coating likely also plays in.
406 hit the nail on the head, I start with carbide burs, then a light go with stones to take out any chatter marks from the carbides, then sand paper on a small drum or mandrill and polish with beeswax and pumice or rottenstone on a felt bob.