If with "B744F", you mean the PMDG 747-400F, it's already compatible with it, and there isn't any need to change or create a door config, not for the regular model, nor for the freighter, since both are already internally supported by GSX.
Of course, "supported", means all the regular exists will work. GSX doesn't support any specific cargo doors (= loading from the left) or cargo operations right now, regardless of the config.