How were large pieces of the A300-600ST and the B747LCF transported?
The answer may be that parts were transported the same way A380 parts were transported


  The A380’s size means its fuselage and wing sections are shipped via a surface transportation network that includes specially-commissioned roll-on roll-off ships to carry these sections from production sites in France, Germany, Spain and the United Kingdom to the French city of Bordeaux. From there, sections are transported by barge along the Garonne River to the Toulouse final assembly line.


From Airbus - TRANSPORT OF MAJOR AIRCRAFT SECTIONS

According to All about Guppys


  The A300-600ST was built in Toulouse, France. 




All the smaller pieces would have fitted into an existing transport aircraft.