I'll take back my comment on the sway bar, since it is a bolt-in type change. If someone went to the effort of changing brakes, a sway bar change is nothing in comparison.
The lack of the VIN stamp is more bothersome than the brakes. Attached is a picture that shows in yellow where you should expect to see the inner fender stamped VIN that is exposed at an area cut or notched out. The orange area shows the general area where you should find the "hidden" VIN. As Bob stated the fender needs to be moved to see it.
If the hidden VIN is there, then you have to think that the driver's side was replaced due to an accident. If that is the case, the brake swap is baffling.
If the hidden VIN is not there, then I would be suspicious of a re-body. I suppose a major wreck of the whole front end might have been possible, but something of that nature might have result in an insurance write off. I suppose if the car was less than 2 years old at the time it might have been a different story.
The other key item (to me) to check would be the dual exhaust support steel. Take a look on the interior of the car with the rear seat removed. Referring to the picture, since the dual exhaust was hung from the floor pan, an additional layer of steel was added to strengthen the area. If missing, this was not an original dual exhaust body, and therefore was not a 390.
Lastly, for color, it is not uncommon to find evidence of the original color in a few key spots, even if media blasted. For a fastback, on the back side of the filler panel between the rear glass and the deck lid is one of those places. See the attached picture of an unrestored example. Another similar spot are areas behind the kick panel. You might only see weak signs of the original color.
As far as the rear axle goes, 67 had a unique situation with the oil fill plug. If the car does not have the correct one, that is another "hit". You can use the search engine to find discussion and supporting pictures for this.
