It may be a head gasket, cracked head, or block.
Hey, how close was that?
While you are fixing the other stuff be looking for an aluminum head. I bet someone here has one and needs to be shamed into taking it off their shop wall so it can be where it belongs! Are you saying that there were pieces of # 6 exhaust seat in #1 piston? Who did that? Was the exhaust pipe hooked to the intake in some primitive turbo design? I guess if a hunk of seat held the intake on #6 open then #1 could have sucked smaller pieces in. It is difficult enough to visualize what happens inside an engine when everything works as it should. When stuff happens who knows!
