Seat's look correct for 68. It has the standard interior. There was an optional "Deluxe" interior available.

The rear quarters and trunk/floor pans are regular places to rust, so it's not surprising the quarters were replaced. Kinda odd that the rear marker lights were removed though. He may have gotten Camaro patch panels and didn't bother to put the lights back in. It is also missing the bird emblem that goes on the fuel door, and the emblems on the front fenders are missing their colour, but that's normal if they are original.

From looking at the pics, I'm pretty certain it was not originally a 400 car. It has none of the extra trim items that a 400 should have on it.

Trunk looks to have a good floor in it, but I would suggest putting the plugs back into the holes to keep it dry.

It's hard to tell from the pics if it's just polish, or if the pain is kinda budget, if you look closely around the edges of the window trim.

overall it looks like a nice fun driver.