Until the cylinder is honed out and measured there is no way of knowing how much of an over bore will be needed. Even then it may have to be bored over some to get a clean surface. Best option is to get another cylinder.
Your pistons may be ok, again they will need to be inspected and measured to see if they are within spec.
If the fresh cylinder and pistons check out to be in spec then standard piston rings are available from Honda, best choice.
If the pistons are bad then you can get used ones and hope they measure out good or there's an eBay seller, cruzinimage, that sells pistons for these models.
Stock head gasket is suitable for up to a 1mm overbore, .040"