Not all SBC had # stamped in them.(castings yes VIN no) The guy is probably just trying to be honest. As far as matching # cars...most are not.(its mostly the corvette crowd that has a proplem) we stamp the engine block and trannies all the time. Would you rather have a original cracked and sleeved "correct" block or a good renumbered one that no one could tell. They now drill the number pad down pretty good and re-weld and deck so that it about imposable to check some stuff. besides back years ago....the #s did not match half the time anyway.