Pieces of steel in cylinder??

good points on brushing out the oil galleries, and maybe it has already been said, but I would be highly suspect of the
piston and rod from the cylinder where the seat came out. The piston could be cracked in the pin bore and the rod bent,
maybe not, but if you plan to re use them, have checked plenty close.

I threw the old pistons out, had the shop press in new pistons. Just picked them up from the shop today, I'll have them take a close look at the connecting rods like you said.