I have no stake in your campaign (except for the fact that love reading your AWESOME write-ups while I wait until The Stars Are Right for a game of my own...) nevertheless you have asked for opinions. Mine is-
Screw continuity.
You already have Hourman , Sandman, Hawkman and Atom fighting with swords,Sandman has a magic girdle, Green Lantern has a fighting staff, your JSA is having adventures unreported in any comic (and so far they are better than the ones I remember reading in the source material!). So why not just declare your universe an alternate one, Wold-Newton style, and toss in ANYTHING you want?
The Ultra-Humanite, Mister Mind and Lex Luthor recruit Dr Sivana, Ibac, Mr Atom and all the Captain Marvel foes! The Marvels are missing, but Bulletman and Bulletgirl team up with the JSA to stop them with Blue Beetle (Dan Garret) and The Blazing Skull dragged along for the ride as a related case leads them to a Chinatown kidnapping ring...
Billy Batson and the newly-empowered Freddie Freeman are in the clutches of Captain Nazi, who now understands that the Power of Shazam can be shared, perhaps even stolen! With the aid of a master spy known only as the Red Skull, and his chemically-enhanced operatives Master Man and Warrior Woman, the Heroes are loaded into the submarine which will carry them to Hitler's Germany, there the Power of Shazam will be transferred to any number of Hitler Youth to create an army of living Ubermenshen Flying Dreadnaughts...too bad some cranky guy with wings on his feet and swimming trunks just started banging on the sub...what's his beef with Germany anyway?
A clue from the Phantom Reporter helps Spy Smasher piece together the clues in time...Mandrake,Zargon, Zatara and Dr Occult all pool resources to gate in a Strike Force...Flash, the Whizzer and The Hurricane scout out miles of terrain and locate the HQ-but the Ulta-Humanite has raised a small army of Super Apes, with brains lifted from the most loyal of the disabled WWI veterans! And there are Monster Men-did Hugo Strange give Hitler the formula or was it tortured out of him by Mengele? Gamely Captain America, The Patriot, Superman and the Blue Diamond battle their way to the main control room making bets on who gets to punch Hitler in the face first(
). But wait, who is this newcomer known as Baron Blitzkeig and why is that British Vampire fellow helping them?
Soon, cackles the time-traveling Per Degaton atop his perch, surveying the battlefield next to a very nervous Adolph Hitler...soon, your Reich will last the Thousand Years I promised it!
Not today, Degaton, intones The Rook, time-traveller from the Warrenverse, and with a puff of displaced air a very confused Vampirella steps forth! Er, do you you know the way to Planet Draculon? she timidly asks Baron Blood-and combat grinds to a confused stop as everyone tries to find the poor thing some decent clothes...
That was just annoying, mutters Degaton-only to gaze into the face of an enraged cyborg stinking of burnt wiring and preserved meat.
I've seen your future, grates Luther Manning, the cyborg known as Dethlock the Destroyer. IT WILL NEVER OCCUR...
...and Hitler dies from a Plasma pistol to the face.
Meanwhile on a distant planet known as Mongo...
So much for the subtle approach, chuckles Ming the Merciless as he signals his War Rocket...
So yeah, throw it all in a blender and pump up the volume, that's MY Two Cents...