director Shane Black, whose next project is an adaptation of the Doc Savage series of pulp novels, talked a bit about the challenges of adapting that material, and then of casting such an iconic role, while doing an IGN interview (embedded below) in promotion of the forthcoming Iron Man 3 Blu-ray.
"Obviously in the books, there's an element of goody-goody that we like," said Black, adding, "Doc Savage was the basis essentially for Superman because his name is Clark, he has a Fortress of Solitude--and oh, Superman has the same thing...that's odd!--but that kind of perfect hero who never makes mistakes is great to a point, and the type of adventure and pulp it represents is so imitated; Raiders of the Lost Ark is essentially a child of Doc Savage. But we needed something more cerebral. We've kept it in the '30s. We've beefed up the rationale behind what it would take to be the perfect person and to be trained as such from childhood and how that would scar someone and what it would take to be a parent who is capable of inflicting that on a kid. But beyond that, we've also trying to be true to the series...while also reinvigorating it and introducing a whole new brand of people to this is a challenge because it's been around for 75 years."
Regarding casting, it seems Black feels it's easier to exclude actors than to add them to the list, citing X-Men: Days of Future Past star James McAvoy--although he does acknowledge that the interviewer's suggestion of Chris Hemsworth could work.
"Here's the problem. They kind of gotta be tall," Black said. "He's the perfect physical specimen and when people look at him, they're overawed by the sort of symmetry and perfection he exudes. I don't know that you could use like a James McAvoy as Doc Savage. You couldn't do it. He's a fine actor, but we need someone big. Back in the day Schwarzenegger was talked about to play Doc Savage. I don't know yet....You need someone magnetic and someone a little but off because that's the fun of the character. He's been secluded from people and kept from any social niceties for so long that he's become a savant."