Market Value and "Numbers Matching" versus "Original Motor"

[PatrickKrook]

The dreaded restamp discussion seems to be front and center (again) lately. I was at Bloomington Gold recently, looking for a good '67 427 Coupe for a client and encountered one in the Gold Mine for sale area. Had all the awards (Triple Diamond), accolades and bonfides, even owned in the same family from new and the same owner since '79. Factory docs also confirm the car as genuine. To the best of the owner's knowledge, it still retained its "born with" motor. The car was awarded an APPEAR OEM Bloomington Gold. One sticking point- at some point during its judging, it was noted on judging sheets that the stamp pad was not consistent with factory.

This is just one example and a sympathetic one at that. There are many, MANY situations where a restamp is present for as many reasons. Some are seemingly innocuous; others are certainly malevolent.

So, the general question is this, on a Chevrolet what is the market value difference between an unfalsifiable original engine and one that is merely "Numbers Matching"- which would include a "restoration motor" or "restamp" on a car that you otherwise known as genuinely factory correct?