I want to start off by saying that I have no connection to DC Comics and I may get things wrong (don't get your knickers in a twist).
I would start off with the JSA as a pre-existing team that disbanded before the events of Man of Steel. I would have most of the original team members dead or too old to help.
The film starts out with someone killing members of the JSA and then the remaining members remake the team and battle the killer(s).
LOCATION, LOCATION, LOCATION
New York City.
The JSA Brownstone.
LEADER - Sandy Hawkins / Sandman
BRAINS - Mike Holt / Mister Terrific
BRAWN - Courtney Whitemore / Stargirl
MEDIC - Charles McNider / Doctor Mid-nite
SPEEDSTER - Jesse Chambers / Jesse Quick
EYE IN THE SKY - Carter Hall / Hawkman
WILDCARD - Matt Tyler / Hourman
WISE OLD MAN - Alan Scott / Green Lantern
LEAD VILLAIN - Vandal Savage
SECONDARY VILLAIN - The Fourth Reich
I'd love to know what you guys think.