Dayson

Johnny Thunder springs to mind.  The only good thing about his comic is the introduction of Black Canary.

GA comic superheroes can also have very silly and/or nonsensical powers or ways to use their powers. And how they acquired their powers can be nonsense as well. In a good way, of course!
 
This book has some gems in it: https://www.amazon.com/gp/product/1631407457/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
 

I think those are more Pulp characteristics.  After the War started the Heroes became to work with the Authorities.  Even Sub-Mariner joined up.

Honestly, most of those are Silver Age in tone.
 
Most of the costumed crime fighters were vigilantes, often clashing with the police.  Batman carried a gun early on, and more than a few of his opponents died.  Superman actively killed several people in his first few years.  Almost all of them were willing to let a bad guy die without putting any effort into saving them, especially if it was an ironic death (Dr Evil was crushed by the gears of his own deathbot, that serves as a lesson to all of us...).
 
That's not to say you can't have those themes in a GA game, just that historically in the comics of the time, things weren't quite so white hat squeaky clean.

Big Bang Comics has created a whole series of superheroes set in the 1940s.  Most are an homage to better known heroes.

A few Golden Age characteristics.
 
1.  The Heroes will be fighting non-costumed individuals more often then villains.  They will be either criminals or Axis spies.  Many will be working for a Mastermind who conceals their identity because they are part of the establishment.   Of course most of the heroes will be too so have some Money and High Society.
 
2.  The Heroes are expected to bring their opponents alive.  That's why no matter what powers the heroes have they will engage in hand to hand combat so they can pull their punches and knock out the criminals and spies out.  You'll have a chance to question them, but the Mastermind will always be nearby to shut them up before they can reveal too much, usually with a secret device that the minion had no idea they were wearing.  Most heroes, especially Bricks, should have Interrogation ("Talk or I'll . . . ")
 
3.  The Heroes will from time to time get captured because the Mastermind will send them into an ambush.  But this will give the Heroes a chance to gain valuable information that will allow them to stop the Mastermind's current evil scheme once they escape.  All characters should have Contortionist.
 
4.  When one of the Mastermind's minions is eliminated for getting captured, this will allow one of the Heroes to infiltrate the gang, and discover a lead to the Mastermind's secret identity.  At least one of the Heroes should have Disguise and Streetwise.
 
5.  The Mastermind is often building an Ultimate Weapon, but needs components and equipment to activate it.  This will lead to thefts and kidnappings of scientists.  At least one of the Heroes should have a Science Skill, and technical skills like electronics, inventor, mechanics, and Systems Operations.
 
6.  In the 1940s is was inconceivable that the Heroes would be vigilantes.  Even Batman in the 1943 Serial was working for the U.S. Government.  So FB: Federal Police Powers and Reputation: Superhero or Crime Fighter is a must. 

Most modern superheroes have a Golden Age counterpart.  There is nothing wrong with taking any  superhero and having them show up back in the 1940s.  Of course if they have Computer Programming they might want to swap that out for Lightning Calculator.

I don't know if you have access, but some of these golden age adventures used to be online. See if your friend has something from that time period he might want to play like the Ray, Captain America, Samson, or the Whizzer. That will help with what kind of powerset he needs. 
CES

Perhaps you should have the players built the characters with a bare minimum of limitations, and at a low power level.  Most Golden Age Heroes were basically Martial Artist with a few gimmicks or one major power.  All should take Code Of The Hero and Superpatriot, and be vulnerable to Ambushes and Treacherous Attacks.  Pulling Punches should be for free.

Yeah go with a really straight forward, simple character: this guy is strong.  This guy is tough.  This guy can fly.  Then combine that with a pulp hero character (he's a photographer for a news organization, he's an archaeologist who gets into wild adventures, he's an airplane pilot that goes to crazy places or does stunts).

Something simple.  Something straightforward.  Something that allows him to use his powers and to generate that feeling of awe among the general populace of just how awesome this mystery man actually is.
 
The classic is to have something go wrong at the World Fair, robot coming to life, a sea monster attacking, some villainous agents coming to rob the great and the good.
 
Really the nature of the PC should drive the detail of the scenario - something tailored to show off the abilities rather than to test them to destruction.
 
Doc