Wow. Outstanding work. What's really difficult to believe is that anyone would try to pass this off without even a half-assed attempt at making it look authentic. If you're going to try a forgery, at least don't insult our intelligence. At a minimum, go on eBay and buy a vintage IBM Selectric, for God's sake.
One thing is clear, 60 Minutes didn't have even a minimally-competent document examiner look at this thing.
Which is why they won't release those examiner's names.