Before you do the valve seal job (which is a good idea anyway) try a trick I've used several times with a good success rate. Overfill the crankcase by about 3 or 4 quarts with Diesel fuel so the crankshaft whips down into the oil/Diesel mix. Run the engine slightly above idle speed for 15-20 minutes with no load (definitely don't drive it), then drain the crankcase quickly while the engine is still hot. The splashing action in the crankcase will do a better job of scrubbing the inside of the engine and freeing up any gunked-up piston rings than you could ever do with a brush. At worst, you'll have a very clean engine to work on when you do the ring job, and it just might re-seat the rings!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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