Do a search on "Wet Up Top", as we have been on this a lot. Four things to a cure, Hastings rings, with the correct pistons for KH, not with the 45 CI ring sets like Eastern likes to supply, cause he is cheap. Get the ones with the wider Oil control ring gap. Use an original KH oil pump with the pressure relief valve. Make sure you have a pinion shaft with about a .090 oil hole in the center of the shaft. We used a left hand philips head screw with a .090 hole drilled in it, and some lock tight to keep the screw in there. It has to have the right left hand thread. I don't have onethat is not in a bike, but you can measure it and order it.
Then put in a anti sump valve between the oil bag and the nozzle on the cases. This will keep it from sumping, and ruining the rings. Just one of these will not work, and to make it work, you have to start with fresh rings and a good fresh crosshatch. You will say, "wow", as you will have more power than you ever thought that a flathead would have! All other cures, plating the cylinders before honing, or boring may help, but never helped me.... Keep the oil out of the bottom, and it will run like a raped ape!