Using Varityper or a photo compositor would create the effect except there was one little problem.
It regards the font. TrueType Times New Roman is a variant of the font created in the 1980s. Slight, subtle differences, but noticable to someone really adept at specing type.
The document was processed using that particular font.
I don't have a good copy of all the available IBM fonts so am reluctant to opine on this.
One of the web experts said that the 4 with a closed top and no foot was used ONLY in Times New Roman and that Times New Roman was ONLY on computers.
Well, I went to the Linotype website and they used Times New Roman, with a four with a closed top and no foot, on Linotypes. Created 1932.
http://www.linotype.com/1540/timesnewroman-family.html
Admittedly Killian probably did not use a Linotype machine for his memos. Still, we want to kill this story, best to be cautious.