Kengineer-130,
I doubt very much the 747 would make a good tanker. Four engines on the wings leaves you very little room for wing hoses that won't be interefered with by jet engine effects. 747 needs a LOT of augmented lift at low(er) speeds, making its fuel burn rate just horrendous. And all that modified lift would play havoc with any aircraft trying to get behind a hose. It could never cope with the speeds required to refuel a C130.
Even a VC10 needs a low-speed drougue and some flap as well as a shallow descent ('toboggan') to allow a C130 to remain in contact for a lengthy refuel. In this config, in level flight, the VC10 burns near 10 tonnes an hour! A 747 does that in a normal cruise - IF (a very big IF) it could go slow enough for a C130 what the hell would it be burning?