If the coat of arms from panel 6 was taken from the 1764 edition of Ahiman Rezon and the scroll was presented to the lodge by William Graeme early 1786, we have narrowed the dating to between these two years. The first is not entirely certain, the latter pretty much is.
On panel 8 Day found a “Dermott Arch” and his secondary source (History Of Freemasonry And Concordant Orders) mentions the Grand Master of 1756-1760. This would say something about the dating of the Kirkwall Scroll. He means that the image in his secondary source can be dated because the name of the Grand Master and the image on the scroll is copied from that very image and can thus be dated. Quite a stretch if you ask me. If this makes any sense, we can narrow down the dating of the scroll to 1756-1786, which is hardly better than the oldest dating based on the image in 1764.
Note that both oldest dates are picked by assuming sources for images on the scroll. Slippery.
Could possibly images of some degrees help narrowing down the dating? Maybe so. If there are indeed “Ark Mariner” or “Templar” degrees on the scroll, the scroll might well have the earliest depictions of both, since Templar degrees are known from 1779 and Ark Mariner only from 1794. It would be really strange if the scroll would predate other earliest mentions by many years.