Excellent work, @PositronGaming! That is looking really nice. I really like your nebula/milky way background, great coloration and depth.
In regards to your question about the writing, I'm sure @jheilman and @chris_s have some thoughts, but I'll share what I've discovered.
Since the whole map seems to be a collaged effort, based on reference we've discovered, as well as Terry Gilliam's preferred artistic medium, I believe the typography (except the handwriting on the clocks and top border) is all Letraset or Zip-A-Tone rub-down transfers. These were widely available and used in graphic design at the time. Also, it would appear all the typefaces are common and easy to find as digital assets.
The vertical and horizontal numbers are Zapf Chancery.
View attachment 833318
The radial numbers are Helvetica.
View attachment 833319
I'm fairly certain the central ring is Arabic.
View attachment 833320
The large ring with faded "script" is the Classic Script typeset. But what is says, is FAR more of a mystery...
though I have a promising theory!
With a little bit of patience and trying to match visible characters we can identify a few letters:
View attachment 833321
XGORNF! ... XGORNF?
What is Xgornf?
However, with a little more patience, more matching letters, then googling the resulting word we can find something
very interesting:
View attachment 833322
Juanelo Turriano is a famous CLOCKMAKER.
My theory is that all the words around that ring are names of famous clockmakers. The only other one I was able to identify that corroborates this theory is "Urgos," which was a German clock movement manufacturer.
My theory breaks down, however, because I was unable to identify any famous clockmaker named "XGORNF." ... I searched some other combinations, but to no avail. Perhaps someone else will have a flash of inspiration as to who or what is a Xgornf.
Hope that helps! And good luck on the continuing journey, I'm glad there is someone else along this road right now.