I guess that busted ring didn't gouge the bore? I would be sure and check the ring groove. New rings don't help much with wallered out ring grooves and it's that top groove that often wears. It's always the top side of the groove. You can see the wear if you look closely. If you run a feeler gauge all the way to the bottom of the groove you won't measure any wear because the bottom of the groove doesn't wear. It only wears higher up where the ring is.
I have seen a lot of nasty looking and even hammered in exhaust seats still seal perfectly but they still needed attention. I wouldn't be surprised if those exhaust guides are looser than a goose.