I will dig up some pics on my work computer late tonight of a cnc port before and after. For example as cnc programs vary and ive seen areas like where the bowl/runner meet that fair better with a cleanup and removing a bit of material. I myself never sand roll anything, just use a finer cutter in a die grinder and like that finish.

Also with the limited heads for small blocks to increase port volume and csa using a cnc head as a start helps since most are done in so called 'stages'.