you weld into the combustion chambers on the heads and change the shape into more of an oval... basically filling in where there is no piston interference, then you smooth them down, basically reducing the combustion chamber size, increasing the compression ratio... i think DPR is popular for this
the hand polishing is just saying it wasn't done by a machine...
and yes, fine tunign his cams with the sprockets or cam gears as we usually call them.