It's too easy
Regarding the forged documents, that CBS is amazingly insisting are genuine, I did a test. I grabbed the original document from here. I cut the word "from", beginning the second line of the first paragraph. I saved the image as a .jpg image file. You can see how the top of the "f" slightly but noticeably overhangs the part of the "r".
If it is not obvious to the eye, save the image, open it with an image editor like Photoshop or even Paint that comes with every pc these days. Enlarge the image and attempt to draw a straight, vertical line between the "f" and "r". You will see how the edges of the two letters overlap the vertical line.
The typesetting term for this effect is "kerning", and permits letters to be squeezed slightly closer, where appropriate, to make for a nice appearance.
The point is, even proportional spacing typewriters from the 1973 era simply did not do this. Proportional spaced typing provided for some letters to be narrower than others, but each letter began to the right of the previous letter. No overlap.
Dan Rather and CBS News had experts examine this document, and they concluded it was the real deal, typewritten in the early seventies.
I think not.