John O., regarding your 9/23/16 10:50 PM post, it depends on who's enforcing the NFPA code or standard (which I assume is the NFPA 101, since you don't mention a specific code or standard).
If the building department enforces the IBC (or an adopted version of it), then they'll review the project under that code and only under that code. If they also adopted the NFPA code/standard, then they'll review the project using both codes. If the former situation is true, then they probably will not care if the wall is 2-hour rated or not; however, if it is marked as 2-hour rated, then they will likely apply IBC criteria in evaluating the fire-resistant performance of the wall. If the latter situation is true (both codes adopted), then it could go either way, but I tend to believe that the building department will use IBC criteria in evaluating the fire-resistant performance.
If the former situation exists (IBC only enforced), then another entity must be requiring the use of the NFPA code/standard. That entity may evaluate the fire-resistant performance based on NFPA's criteria, which appears to be a little more flexible than the IBC.
Regarding IBC Section 703.3, it uses the words "engineering analysis," which implies a review of the system by a qualified engineer. You could probably get a fire protection engineer or a materials engineer to provide such judgments (many manufacturers of fire-resistant products, such as firestopping, provide this service, but I'm not sure if gypsum board companies do).
I'd like to hear what the outcome is of your meeting.