[TimG]

"The Corvette judging bodies have no problem with restamps"

This is not true, if engine judges smell a restamp, the engine is busted. Heck, if they don't like the look of an original engine, they bust it. This happens on a regular basis. Some judges estimate the number of broach marks per inch on a pad and will bust an engine for that.
Bottom line is that if the restamp is "typical factory production in appearance" it will pass. This doesn't mean that a restamp is OK, but there is not enough evidence to prove that it is a restamp, some are done very well. Something like being innocent until proven guilty.
Granted, lots of restamps make it though NCRS judging, but if it is an obvious restamp, it won't. As I said, lots of original engines don't make it thought NCRS judging. I've seen it personally with vehicles I know about. The pad has to have the appearance of "typical factory production" if it does with out question meet this criteria, it passes. If it doesn't, it is busted, original or restamp.