Engine S/N

[1970Dart340Swinger]

First, I apologize if I'm asking a question that has been asked 100 times before. I searched all the threads and didn't come up with an answer.
Our recently acquired 1965 Dart with 225 slant 6 has the following identification stamped on the front right side of the block under the head:
O 225 R822 2F
From what I have read on the forum, I'm interpreting this as (o)=1979 engine, (225)=225 cc, (R)=passenger car, (822)=built August 22.
Is this correct? And what does the 2F mean?

 

[volaredon]

Wouldn't be a 79. If it were it would have an "E" after the 225, as all after sometime in 76 had cast crank not forged // and no cast and forged crank won't interchange within the same block.

 

[1970Dart340Swinger]

Wouldn't be a 79. If it were it would have an "E" after the 225, as all after sometime in 76 had cast crank not forged // and no cast and forged crank won't interchange within the same block.

 

[1970Dart340Swinger]

So if the "o" is not 1979, what is it? And what is the interpretation of the entire string?