Your door can be found on any 2 door post Nova from 62-65. There may be some tiny differences, I don't know for sure. But they are the same "body" and the doors would interchange. The moulding holes would be the biggest problem. I don't know about the 65 Post but I know my buddies 65 H/T had no mouldings at all down the center, it had the moulding was at the top above the upper body line. So if you got a 63 with that big old moulding down the side and plastic clips you would have some big holes to fill.
Brian