Classic Sporting Arms-Whenever I "Google" Ruger #1's this is one of the sites that always comes up.
I've never done business with them, but they have a 1A .308 listed when I just checked.
I have no idea which version your Dad wants, but they say they can locate rifles for you.
I don't know which versions are collectible, but everything I see listed is always on the high end of the dollar scale. They may be able to tell you how many rifles meet your criteria. They're asking $1750 for the one they have. $1100 more than I recently paid for a 30-06.