Nathan, excellent work. I hope that everyone reads them and replies with sensible questions and answers.
e) Evolution class bikes must have No linkage suspension, No disk brakes, and Air cooled motors.
Could this be worded a little different so that it leaves in no doubt what it means?
Maybe,
Evolution class bikes must have been manufactured with Twinshocked or cantilevered rear suspension and Aircooled motors and Drumbrakes. All parts from those bikes are permissible as are after-market parts of this era.
a) Modifying your bike with other major parts from a different technology or era is not allowed.
Yes I know it's long winded but it is very self explanatory and I think very water tight. Anyway just a thought and obviously open for discussion re the old and new interpretation of the existing rules.