Warwick said;

"the question is did the AE's want to express it. AS you have just admitted You don't even know if they had the mathematical means to do so"

Yeah, to express the exact value of 311/99 in Eye of Horus fractions. So who said they had to do so? That would be the reason why they used the 311/99 fraction for the GP dimensions. It's already in its most reduced form, other than expressing it as 3 14/99. I gave a possible seked for the slope but it would be less accurate than using the actual fraction itself. All they would have had to do was lay out such a right triangle on the ground and then use it as the template for making wooden set squares of that exact angle. They didn't need a seked, they just needed a bunch of these set squares. Why would anyone want to keep measuring out the seked when all they have to do is hold a set square up to the stones? That's exactly how they made the slope on the casing stones, just drew the slope on there with a set square. For maintaining the slope of the core blocks they would have used larger set squares, spanning several courses. All they had to do was sit it on one of the courses, at a corner, and check to see if the other side (going the other way from the corner) sloped at the angle of the square.

Sekeds are fine to explain the theory behind producing pyramid slopes but they are only usable in the real world after you use them to make a set square because you need a perfect right angle. If you happen to want to make a pyramid that doesn't have an exact convenient seked, as is the case with the GP, then you have to make your set square by laying out the exact slope you want, in this case by making a right triangle with sides of 311 and 396, using digits or whatever unit is suitable to the size of set square you want to make.