I was just reading another thread when i realized something, on more than one occasion rockers have slid out of place on these 6G motors for a couple different reasons. It makes a ton of noise and since we now know there is no metal in your oil and cylinders have been scoped to show minimal damage (possibly normal wear and tear of an old motor) It could be very possible that some of your rockers have become wedged sideways holding the valve partially open when it should be closed fully. since there is no valve marks on your piston You should pull your intake and valve covers before we get too far ahead of ourselves. If this is in fact the case with your motor we can just ship you the replacement parts or possibly make a weekend trip to New Mexico (if some of the guys want to carpool) for what i'd call a minor repair. your weather is better than ours at the moment.