For you guy's trying to salvage an old engine where rings are unavailable, or hard to find. I have been using this method for derusting old tools, or parts for some time. Use a plastic container. Get a box of Arm & Hammer washing soda. Hang the piston upside down by the connecting rod, suspended by a metal rod in the plastic container. Mix soda, and water, one tablespoon per gallon is enough, and pour into container to just cover the piston rings. Put a metal plate connected to the pos. lead of a battery charge in bottom of container, hook neg. lead to metal rod. Use a jumper lead to submerged plate. It will take some time, but by electrolys, it will attack the carbon, and free the ring. I have used this method to derust those old double line gas tanks also. Nov.28, cabin fever already.
