Just a hobbyist here. Ive cautiously done a set of 915 360 heads. The intake runners and bowls I removed only enough material with rolls and stones to remove the casting slag, lumps, flash and surface roughness and unevenness. Tear dropped the valve guides leaving their height intact. I didnt use a tool such as the Helgesen's E-Bar tool for the pushrod pinch but rather used the rotary stone and took down the as cast finish. Did same to exhaust port and bowls but added a polish to the them as well as the combustion chamber.