Thank you again for the expert feedback.
The irony of this situation is that the building code doesn't require a 2-hour rating between occupancies like F-1 and B (our situation). It is NFPA. If NFPA is the source of the requirement, then does the limit of 1-hour calculated assemblies apply?
Also, in 703.3 "Alternative methods for determining fire resistance", it offers the approach of "Engineering analysis based on a comparison of building element, component or assemblies designs having fire-resistance ratings as determined by the test procedures..."
Doesn't this mean that I'm not restricted to only using published designs? Can't I intelligently extrapolate using components of the tested designs?