There are a lot of ways to tell if panels have been replaced.
The most obvious way is usually non factory welds. Reproduction panels are often different shapes. Sometimes restorers use panels from different years or reproduction panels. The lack of factory sealers and deadners can be a clue. Thats just a start.
This gold car has no attachment points for the hood seal and no big block oil cooler (requiring modification to the radiator support). I dont know of its been replaced, but the point is the car should have been inspected in person and the questions were never even asked. At least not in the open forum.