Old jug or not if I put new rings in I make me a flapper by cutting a slit in a 8-10" length of 3/8" wooden dowel rod and then I cut a 1" wide piece of 600 grit wet dry sandpaper fold it in half and slide the center of it into the slot in dowel rod and then chuck the dowel up in my cordless drill and use that to put a good cross hatch hone inside the jug, on these engines with a chromed bore the bore is much harder than the rings so you want the cross hatch to actually wear the ring into conforming with it and that is what makes for a good compression seal between rings and the jug/ cylinder wall.
You are correct Thunderhead289