>>Looking along the shaft then the angle deflection from the north precessional circle is only +/- 3.37 degrees.
Setting this angle onto the circle you can see that Alioth is far from view.<<
I don’t follow you here. I am not an astronomy expert so can you clarify. What I know is that when Kochab and Alioth are at the descending angle altitude 26.531 deg then their azimuth is 10.13 and 13.72 degrees respectively. Thus their difference from the 4.09 degree entrance azimuth is 6.04 and 9.63 degrees respectively. It makes no difference that Kochab is closer there is no match in any of the two.

The shaft angles might have been planned with other things in mind. For example the latitude at transit of Thuban at March 27 2466 BC as seem from my house is equal to the South shaft angle of the Queen’s chamber.