This is exactly why the whole "numbers matching" thing is so goofy to begin with.
People freak out about a few numbers that were just stamped on the car. What does it change about the actual car? Nothing. If it has the right casting number, and the right production date range, and a blank VIN plate because it's a factory warranty block, why is that worth less than one that has some numbers stamped on it? Because it wasn't "original"? It's the same block, cast at the same time. The original engine and that warranty block could have been sitting side by side at the foundry, doesn't make a lick of difference to how the car performs.
For the record, I'm not condoning somebody stamping those numbers and passing it off as original, that's still fraud. I just think it's stupid that it will even make a difference to begin with.
If you're gonna pay a buttload more money because it's matching numbers, well, I guess you'd better do your homework.