Right engine

Is there a way of telling if 67 R/T has the original engine in it? I have been told that the cars starting in 68 the engine serial number was part of the vin.
I know that you can tell the year the engine was made by the letter on top front of the 67 engine. Also was told that the only thing different about a 67 R/T 440 was a little hotter cam.
Author: chuck1934