I am in final planning of a new home build in zone 8 (8800 ft elevation). Flat building site, slab on grade construction. 
The local HOA has a design requirement that 25% of the exterior be covered in a natural stone. I’ve not finalized a stone choice, but i’ve found some stone veneer around 12.5 psf.

Based on  2021 irc, table 703.15.2 and assuming 15psf for the veneer, I have a fairly tight window to hit my insulation goals. My current plan for the stone veneer over framing is from inside out :

24″ OC 2×6 advanced framing (Batt insulation, R-21)
sheathing with integration WRB (ZIP or similar) installed and sealed per manufacturer recommendations
1.5″ polyiso exterior insulation (R-9.6)
vertical  2x furring strips nailed to framing with .162″ x  5″ nails (8″ spacing)
1.5 polyiso(R-9.6) installed between furring strips
stone rainscreen, or felt+lathe
stone veneer

Since i have a minimum amount of stone requirement, I would like to continue the stone veneer approximately 16″ down over the foundation walls, reaching to, or just below, grade level. I plan to apply exterior insulation (EPS preferred) over the foundation walls. There are some older posts here that mention using stone veneer as a protective layer to the foundation insulation, but I’ve not seen a detail on this assembly. Given the code table cited above, it seems like i could continue the insulation and furring strips (ground rated pressure treated) down the foundation.  

Does all this seem reasonable?
Opinions on if the pressure treated furring strips would meet code for sub grade contact (I think so since that are not structural).
Any recommendations on how to attach the furring strips through the insulation and to the foundation?

The structural engineer is starting their work in a couple of weeks, and i have not discussed this specific topic with them yet. 

The other thought i had would be to do ICF foundation, and locate the framing such that the stone can continue down the same plane on the ICF (assuming i can find recommendation from an ICF manufacturer on attaching stone veneer).  I’ve seen some developments in the area where the builder did the first buildings with ICF and then switched to conventional concrete on later builds. I am not sure if this was just a cost thing, or if there was another reason. I talked to some of the sub’s and no one knew why they switched. 

In either case, are there any recommendations on the transition point from framing to foundation, specifically flashing detail at that transition.
Or other thoughts?

I’ve attached a drawing i made to try to work out the assembly details. 

Any thoughts or suggestions are greatly appreciated.
Tracy