So in the CRG data base of Z/28's, 302 engines, if enough data points were observed, there would be a pattern of dates that the 302 was produced, and also a pattern of pad stamps for a given batch of engines. And then it could be determined if a pad stamp was legitimate based on the date and the pad stamp. Same as when a distributor stamp is observed, and someone comments that it is a "known good date". If that's reasonable, then I guess the next question would be: Are there enough data points in the data base now that allow for these patterns to be known? If so, it would make faking a block very difficult for anyone without the data base or knowledge of the patterns. At least if their forgery had to pass CRG inspection.