I can't say exactly unfortunately, because not only was his on a body lift, but also on a heavily modified tunnel to raise it up. So not sure how much of the original trans shifter was showing through the floor, and not sure how his rear bracket mounted relative to where it would normally be expected to, height-wise.
So while his main rear bracket looked largely un-molested, his floor was altered from where the ramp started in the rear almost all the way to the firewall.
The interface at the trans lever was altered because the ZF is different shaped than the NP435, but not sure it was all that much. Maybe a refresher in the way of a pic of the shift lever as it comes out of the transmission is in order. Then compare that to the NP435 and see what might need to be done.
Nobody does both that I'm aware of. The GearBanger IS a short-throw shifter. Just a round-a-bout way of doing it compared to the more traditional method. The idea was not only to reposition the shifter location, but to shorten the throw at the same time.
I don't know how they compare percentage-wise, and maybe the short-throw stuff has a higher ratio of change, but you still get some of the benefit with the GearBanger.
After all, the old NP435's were not exactly short-shifting boxes themselves. A little improvement was called for even while moving the shifter location relative to the driver.
I don't think you'd hurt the installation by using both, but I have no way of knowing just how short the throws would be with both.
Paul