Would not hurt to check that exhaust valve guide while your at it. Depending how back pressure the muffler has a worn valve and guide could let pressure past into the crankcase which then vented thru the carb. Just thinking here because I see a lot of Briggs side valves with worn exhaust valve guides that mimic bad rings.
As re-ringing before ordering parts check to see it needs over sizing. If so you will need a ridge hone to true the cylinder.
