In the novel, Clarke already said that Taprobane (Sri Lanka) was a fictional place and that he liberally moved the island "800 km south" in order to have it at the Ecuator. He also doubled the size of the mountain.

He aknowledges that there are better spots at sea level i like the island of Gan in the Maldives.

Also, in the novel the solution was a tape made of diamond, which comes to be carbon nano tubes by our current technology.

And more important, he made a novel, not a engineering paper, but I still love it to the smallest bit.