Well, there is something cool about the road not traveled science. This could THE dieselpunk move. Unfortunately, that distinction wouldn't sell many extra tickets and could inflate the special effects in big way. So maybe it best to leave that road not traveled not traveled.
The recent DC Doc Savage comic did a very good job fleshing out and adding depth to the Fabulous Five. The movie could do worse than take cues from it for their portrayal.
One of the problems I can see the movie Doc Savage running into, is the desire to give him a motivation. Doc Savage's reason work to improve the world and to fight evil isn't explained. At the time, I guess people didn't feel a need explain why a person would want stop the bad guys and help those in need. I'm think now the desire would be to explain it. Show how his Uncle Ben died because of his self-centered behavior or some such. I'm not sure whether audiences really demand this or not.
IIRC, Doc Savage was basically raised by his dad and other scientists to achieve perfection in darn near everything and to fight evil and help people simply because it was the right thing to do. They did give him a motivation in the first book by having his dad killed off, though.
What will be interesting is if they address the whole issue of Doc's secret hospital, where he performed blatantly illegal operations on criminals that removed their criminal tendencies.
To address another point above, if Black intends to set his movie in the '30s, then he may to have to jiggle their backgrounds if he wants gender and racial diversity in the Five, since four of them were high-ranking US military men during WW1.