Welcome to owning a 65, remember it is a 41 year old car and has seen a lot of traffic crashes since being made. My car when I bought it also had a different buck code plate on the door. All I figured was that the car had been in a crash and they replaced the door with a donor car from a wrecking yard and did not take the other cars buck tag off. No big deal. I got Mark at Capital classics? to make up a replacement bucktag for the car.
Put the chasis number on the web page and someone will decode it for you and tell you exactly what you bought, Good news about the floors though. Carpet is pretty cheap and easy to replace and makes the car look much better inside so its not all bad.;_