ZF6 / 7.3L - New Valair Dual-Disc dragging in reverse

Hey everyone, looking for some technical perspective and maybe some advice on how to handle a shop situation.

I have a 2000 F-250, 7.3L, ZF6 manual.

Just had a brand new Valair Dual-Disc organic clutch installed.

The Issue: I’ve had the truck back for a day and it’s fucked up. I have to mash the pedal into the carpet to get it to shift, but the engagement point is at the very top of the pedal travel. Most importantly, it resists/grinds going into reverse when the engine is running (shifts fine when off), which tells me the clutch isn't fully disengaging.

The mechanic mentioned he used a lengthened slave rod because the "throw wasn't long enough." My research (and common sense) says this is a band-aid for a geometry issue. I suspect the clutch fork is slightly bent or the pivot ball is worn, which is "stealing" the throw needed for the dual-disc setup. From my research a 1/8” difference of pivot ball wear (or fork bend/flex) translates to 3/8” of extra throw the slave cylinder would need to output.

After driving it for about an hour on surface streets, I texted the mechanic explaining that I think we need to reset to factory specs using a reinforced fork (like the South Bend T905) and a fresh pivot ball so we can go back to a standard slave rod. He hasn't responded in over 24 hours now. He previously told me "if I order the parts they always work," implying the issue is with the truck or the clutch, not his install.

1. Am I right that the lengthened slave rod is a red flag here? The documentation from Valair does not mention anything about modifying the slave rod, and Valair customer support said despite it being a dual-disk clutch it is designed to work with stock geometry for the ford ZF6.

2. Has anyone else had to swap the fork/pivot specifically to get a dual-disc to release properly on a ZF6 or did they reuse the original fork & pivot ball?

3. How would you handle a mechanic who is shirking accountability after a major install like this? I don't want to roast my syncros or the new pilot bearing driving it like this.