The question isn't whether a typewriter could produce the documents (even though I know they can't). That is playing into the libs hands. If they can pretend that's the issue, then we have an interminable hunt for the one document that will prove they are real. Of course, there is no such document.
This is a bad idea because by implication you are saying that if a typewriter could produce the same document, then they are real. That's ridiculous. That would mean no documents since 1975--certainly since the advent of word processors--could ever be proved fraudulent. The issue is a combination of the likelihood even a similar document could be reproduced on a typewriter and if so, what would you have to do to produce it? Then the issue becomes, do any of the other TANG documents on file have any of these characteristics? Of course they don't. These documents are fake. But I've seen the trap of trying to prove a negative fail too often. That is not the standard. It will give libs all kinds of opportunities to claim a certain typewriter easily does this or that without ever addressing the issue of the myriad other problems there are that show these to be fake.
If it's a test you want, I'd like to see CBS instead put on someone with the typewriter they claim could have been used and show that person creating the documents. Show them centering the header, show them changing the balls to make the superscript, show how expensive the Composer was, and produce any other document from the known TANG files from that era with the the characteristics we've been talking about, other than these memos. Then show them superimpose the headers over each other and see if they align.
Many forged documents can only be shown to be forgeries by 'proving a negative'. There are few, like these ones, that can be positively shown to be forgeries.
Suppose that somebody had a photo of Einstein standing in front of a blackboard with a bunch of seemingly-random numbers on it. Would the photo be plausible? Perhaps. Suppose a check of the Illinois Lottery website showed that the numbers on the board were drawn on 1-1-2004. Would you still consider the photo plausible?
Given that the positive proof of fakery exists, the notion of 'typewriter searching' is silly.