Hmm nice! That reminds me of how I used to true up an aluminum head for a small engine. I would take a nice piece of flat plate window glass and lay it on my shop table.tape a peice of 320 grit down,and rub the head in a circular motion .Im thinking this would work for a phenolic body also. Those well plugs on the other hand ,if leaking ...well those are a bit of a problem to remove without destroying.