747 notoriously uses Rand airport, which is 1500 m long, hot and high and, even worse, just 15 m wide.
My understanding is that this has only been done once and it was the aircrafts delivery flight to the airfield museum / display park?
I doubt that you would be able to get airborne again but I don't have the graphs to hand so I may be wrong here. (Rand is about 5500' amsl)
Regards
csd