Dived into some work on the big Matchy today. Combined tow seats to make one. I had a replica seat already. The seat that came with the Matchy was bigger. So chopped them up. Black paint. Seat is done. Just need 2 new big springs for the seat to bounce me around on now. Seeing how bunged up around the bottom of the push rods is I took the barrel off. One big ugly piston. I love 500 singles. This one has some scoring. Inlet valve seems to have been kissing the top of the piston. There is no scoring on the bore that I can feel. Should I replace the piston and hone or re-bore to match the replacement piston? Don't know yet.