FYI, they did NOT stamp the VIN's on the engines in '67. You would need to verify the date code builds of the drivetrain hardware against the build date for the car, and if they are an appropriate time gap ahead of the car's build date, you should be reasonably sure that it's for real. As someone else mentioned, the first verification I would do would be to verify the VIN against the fender tag, since you can't be sure that got swapped in the sheet metal transfer. It is a fairly low production car, and there aren't many left like it, so if it the numbers check out, I would grab it!!