I concur with the others... this seems to have been carefully renumbered.
This photo of the front of the frame enlarged 2X and also shown in a negative image appears to show the 'ghosts' of previous numbers. The photos on the right of the number stamps on the toggle parts are obviously stamped over previous numbers that were not ground down far enough to remove them.
I think the takedown lever has been ground down and then renumbered and the trigger may have been unnumbered before being struck with the digit one (in the wrong font for the period).
[quote] He was an FFL in the 1960's and kept good records. <hr></blockquote>
If this is so, then what did his records show about the origin of this pistol?
These parts will assemble into quite a shooter. If it were legally mine, I would search out the correct 6 inch barrel ( the 6 incher that you show may be a standard barrel and the front sight boss may not be high enough to allow for placement of shots at point of aim with a standard front sight) and then have this assembled and rust blued by Thor. Keep your origin documentation to keep you legal. Have the pistol marked in an obvious place as a rebuild to prevent it from being sold someday as an original #1 Navy... AND THEN ENJOY SHOOTING IT!