To me evo rules are simple. Any part from any evo legal bike can go on any evo legal bike.
Eg 1979 CR can have 1981 YZ465 43mm forks, 44mm Fox forks or even 1984 40mm Husky forks, but not 1981 or later CR forks. Just like any pre85 legal bike can use parts from any other pre85 bike.
Just because something is or has been excepted in the past doesnt mean it has to be now or in the future.
This is the big problem for evolution. It is too open to interpretation. I have tried to explain my take on it, but understand if it is wide of the mark with regards to history.