confused on casting numbers on engine

I have a 1965 dodge Dart 270 convertible. I had the engine rebuilt. When receiving the engine back from the rebuilder it had a tag affixed with my name and saying 1964 225. I did some research and the research prompt indicated it was a 1966 motor. The casting numbers are as follows:

2463430-5
12224 ( i was thinking produced 12-22-1964)
1209 ( ? )

any thoughts