Sounds like blown seals every where. Folks this is where reading and understanding the shop manual comes into play. Overfilling would not necessarily blow out piston rings, but it could. I think the rings were probably on their way out any ways. What I would do as Okie says is do a complete overhaul, and replace every seal, piston ring, and check the cylinder head for leaks, valve seals, and seats etc, Yeup I know 4 strokies too. LOL.! Make sure to replace all gaskets, wrist pin bearings, and wrist pin keepers, be sure the whole bike is spotless, because this is open heart surgery, and you wouldn't want your doctor eating tater chips during your quad bi-pass? Your bike will thank you, LOL! Good luck, you can do it man!
Red Rider...