You can use the service that NCRS offers via www.chevymuscledocs.com
Certain VINs may be missing, but NCRS refunds the $50 fee if your car's details cannot be found.
Be aware that the dealer provided is the dealer the car was shipped to from the factory. In most cases, this is also going to be the selling dealer, but there is always a chance that dealers traded stock.
Without solid authentic documentation, or verified drivetrain stampings, no way to be sure what engine the car had from the factory.
Your badges could've been added by a PO.