Well.... in speaking to some prior owners of that 'One and only on the Planet' giveaway car (Fathom Blue to be exact), the car had been missing it's original engine block for many years. So, it's hard to back up the claim of it being a COPO 427 car. This car was YS-8008, 4speed, FB w/ black interior, #413665 sold new from Jay Kline in Minn. MN and had the 'hubs' option, (
we think that's code for the Pontiac wheels).
The Ermine White '68 Yenko Camaro has a peculiar plate riveted in the door jam that says 'SPECIAL DRAG CAR' or something along those lines. I think the jury is still out on this one, as the owner has some convincing paperwork that a COPO 427 car could have snuck out the door as an 'export' model. However, I don't think anything has been confirmed - yet. This car has a red interior, is a 4speed, is stock number YS-8023 and was sold new at Branine Chev. in Mulvane, KS.
In regards to a specific engine stamping, I think you are referring to the 'MV' code. There are several examples of MV coded blocks, both that were recovered from transplanted cars and from those that were not transplanted, where the bore is a 396 bore - not a 427. Although earlier publications eluded to the MV code as a COPO 427 application in the Camaro, the actual blocks do not back that up claim.