Ideal Shift points for 904

I will check, from what I read the throttle should be WOT and the KD lever all the way back?
yes.

But as you can imagine, the KD mechanism, only delays the upshifts when it is actively adjusting the pressure inside the trans.
To see what I mean; flip the green return spring off the KD link, then gently push the rod to the back until you feel resistance, then hold it there. Next open the throttle until it stops at the back of the slot. When it does, this is now at the throttle opening required for the KD link to begin doing something .
Obviously, at lesser throttle openings the KD mech is NOT DOING ANYTHING at all.
So , in this dead-zone, is where the governor is commanding the shifts. If you want the trans to behave differently in that zone, then you will have to make changes to it; as detailed in my earlier post.