Hang on just a minute. Your initial post said the motor would turn over fine with the C-body pan/pickup. You suspected the B-body pan/pickup was the culprit and it wasn't. Now that you still have the problem, you're prepared to tear the motor down looking for something in the combustion chamber? The only thing I've ever seen crawl into a combustion chamber without assistance is mice. If it were me, before I started pulling the entire engine apart I'd be pulling the valve covers to make sure I didn't just lose a valve for some reason .