I would guess so but, as in my case, I bought just the bare hull/tubes, rated at CAT B. If this was the state of the boat type for assessment, it may then have to be reassessed after final build and be reclassified. This may be standard practise and it would be interesting to see what category is applied to final, ready for launch, boats of the same type. If the type plate was the same, it would be worth asking the question again.
Of course, the assessment may take place on a completed boat with the highest, likely in practise, GC and then there is not a ploblem for all other builds. (I'm a bit cynical, and doubt if this is the case.)
However, since ribs are often custom built, I feel it would be reasonable to ask of the company, what is its category at completion.