With one little nitpick: you can do that without removing the Golden Age characters from the shared Earth; just tell the tale on another Earth.
And frankly, you don't need a Multiverse for that. In the 90s, what you're asking for would just be an Elseworlds story; and if it sells well, it can get a sequel. The only thing you really need a Multiverse for is if you want the heroes of the various Earths interacting with each other. Frankly, if I could retcon one thing in the real-world publishing history of DC Comics, I'd nix Infinite Crisis and double down on Hypertime.