I think just adding two more gearboxes to this falcon would be a disservice to this model. Bandai very faithfully recreated the falcon as it appeared in 1977, and if this falcon were to be modified to be the ESB falcon, I personally would want the whole nine yards - so additional gear boxes w/ two more landing gear, brand new maintenance pits to go with those gear boxes, the little squares ILM added on the bottom hull for more lights, the mods to the bottom jaw for those lights, drilling out holes in the front of the mandibles for the head lights, and the many greeblies that fell off and were replaced or glued back on incorrectly by the time of ESB.
Of course, this is just my opinion. If someone can manage to modify the pg falcon to accurately represent the five footer when it was used for filming ESB, I will be thoroughly impressed