I can guess the number is 12,000 km. So. Plus or minus. Why do you think you need that info, for what logical purpose will U used it for?
To compare it with reality.
So, if the distance between the two on the Gleason map is 12000km, what's the diameter of the whole flat Earth?
If the Gleason map is an accurate map of a flat Earth and the distance you propose is correct, it would mean that the land masses closer to the North Pole are much, much smaller than they would be on a globe. do you agree with that?
have you ever looked at the Gleeson map?
You sure that this is 7000 miles according to the Gleason map? that would mean the whole diameter of flat earth would be about 10000 miles.
So, what are you doing about it?