"The height that the 2.5 slides arc is cut to makes it a lot more open than the 2.0 even when the idle screw isn't screwed in all the way there's space for the engine to breath and I can finally use the carb how its intended to be used turning the mix screws have an effect as they should and the idle mix screws work properly."
For example, are you are speaking of the 36mm "cutaway" as in the drawing being a lot more open?
This does not control proper idle, it is the transition fuel/air circuit off-idle and before full needle jet flow, the 41mm dimension is the throttle edge.
Your throttle slides may have been modified.
Difference between cut-away numbers
2.5=.156"
2.0=.125"
cliff