Sorry for the delay in the postmortem. I'm pleased to say that the design we proposed was accepted for a 2-hour rating. I'm attaching the explanation of the design logic that we submitted with the architectural drawings.
In a nutshell, we argued that the only meaningful commonality among all 2-hour rated walls is a double layer of 5/8" type X drywall. All other variants in wall configuration don't seem to be highly relevant.