You can't go wrong cleaning it up inside. Do just exactly what you described. Take off the flash and match the cylinder transfer ports to the case. Clean up the case/cylinder gasket to prevent any disturbance in the flow.
(Snipped from post #18)
One thing nobody has commented on, is warranty responsibility.
A little while ago there was a thread here where an engine lost the screw that holds the choke in place, the screw was digested by the engine, with grim results. Increadibly enough, the supplier of the engine refused warranty responsibility, because the engine owner at one stage had taken the rear-mounted carburator off the engine, in order to install this in the plane. The fact that the choke screw had not been taken off in this process, seemed irrelevant to the supplier. What was important in his view, was that the engine had been "modified". (Increadibly silly argument.)
So where do you stand on warranty issues if you dismantle the new engine to polish it inside???
Magne