The piston is a 2nd oversixe stock CZ. they are all marked _ 1 2 3, A B C, X Y Z. So a first oversize could be 1AX, 1AY, 1 Az, 1BX, 1BY, 1BZ, 1CX etc. They are sized to the original bore taper. Very accurate engineering. Any second over rings will fit, no I don't have spares,
Cheers,
D.