Agree that the 2" guns bring much more that the standard 4" model 63s.
There is a possibility that this one had a parts swap (barrel, shorter extractor rod) from the longer barrel. The only way to confirm it is an original 2" is a letter of authenticity:
http://www.swhistoricalfoundation.com/swhf_letter.pdf
Also agree that someone has changed the SN prefix from the correct BFV to "8"FV by engraving the stamping more deeply. I don't know what would motivate someone to do this but the original SN has been altered...tricky situation from the legal standpoint.