I inherited two new pistons with a cb350 I purchased. They are in white boxes with "CB350" and "030" printed on the front of the boxes. The number "581123" is penned on the top of each box. The pistons both have ".030" stamped on the top of the piston. The actual measurement of the pistons is 2.525" or 64.1 mm. Presumably, these are first overbore (0.030"). Three questions. Do the measurements correspond with the assumption that these are first overbore pistons? What would be the required finished dimension of the cylinder bore to fit these? Not knowing the maker, are these from a reliable manufacturer? I have no additional clues to offer since nothing else is on or in the box.