Hi  I’ve built a house in NY Zone 5 from insulated hollow clay blocks (Porotherm Climamur36). Typically around the world people who use this material clad with stucco. I don’t especially like stucco and it’s rare in NY to see a stucco building without stains. Part of our reason for using the clay blocks (98% of the homes built where we live are stick construction) is to have the home last for generations, so our approach to all aspects of the build is with an eye towards everything needing minimal maintenance for the next 75+ years. With that in mind we plan to clad the house with full bed stone. Mason’s who would take on a job the size of ours are few and far between near us, so I’m trying to gather as much information as I can while we search. We’ve been to numerous stone yards and interviewed some mason’s. The 3 methods of install that we’ve been advised to use are 1) Have a 1-2″ air gap with weep holes and/or a rain screen. 2) Have a 1-2″ gap and fill it with concrete. 3) Put the stone against the clay block.  The Porotherm will have gotten a WRB before starting with the stone. 
I’m looking for advice.  Thank you!