To do it "right" I'd be inclined to go with Jglenn & pull it down. A new set of rings won't set you back much & running a cylinder hone brush up & down a bit will smooth out the walls & get you a good (better anyways) seal. I did a locked up Briggs this way a few years back & put it on a go-kart that's still ruining my yard on a regular basis. Think the ring set cost me about $10 on ebay.
