I have searched, without finding a single dogleg jack listed for sale, through the following catalogs and pamphlets::
1946
1948
1951
1954
1955
1957
1965
1972
1973-74
1975-76
1977 pamphlet
1978
1978 pamphlet
1979
1982 pamphlet
1984
1988 pamphlet
1990
1991 Anniversary Flyer
1992
1993
1994
1996
I started finding references to the dogleg jack as a knife style starting in the 1948 catalog.
The pony jacks (models 21 and 22) are the closest in closed sized to the OP knife, but the 21 and 22 are always depicted with a clip blade.
All line drawings of the dogleg, and only of the dogleg, show the spear/pen combo.
I found a couple of references to the Camillus dogleg jack, both stating that they had concluded that the knives were made in the 1960s based SOLELY on the stamp.
I'm starting to lean towards the conclusion that the dogleg had a VERY short production run during the 60s. If they were ever published in a Camillus catalog or pamphlet, it was in one of the years 1960 - 1964 and 1966 - 1969.
Unless someone comes up with one of these "ghost" catalogs or Phil Gibbs has some info tucked away, the only way to track it down would be to go through old magazine archives of outdoors magazines at a major university's library.
The other possibility would be to find out what happened to Tom William's stash of old Camillus "S-cards" after he passed away and search through those.