74 Duster 4 speed adjustments

The Z-bar is just an equalizer. It it runs at some angle other than stock, then so be it.
The secret is in getting the .080 plate departure together with the proper freeplay.
This is the job of the ratio in the Z-bar. The outboard lever length is fixed, cuz the down rod has to stay in the hole. But the inboard lever length,controls the departure/freeplay.
It would appear that this new clutch of yours needs a new ratio. I think there are three 67 to 73ish A-body ratios; one for the slanty and one for the big boys, and one for the SBMs. The slanty will not interchange, cuz it is too long. The BB is all squirrely on the inboard end.Yours appears to be correct.
If the inboard ball is too high, it will steal ratio, by moving in an arc instead of fully longitudinally.
So, I would look to the ball height first. It should be the same height from the ground plane as the outboard one, and in plan-view, on an imaginary line 90* to the centerline of the vehicle, and ending at the outboard ball.
Once you have that set up right and you still have problems,then you may have to lengthen the arm.
That's what I think.