Captain Marvel -Public Domain redux

As part of a facebook Public Domain Heroes group, I will be re-imagining some heroes from comicdom's (gone but not forgotten) Golden Age.

Apparently, the original Captain Marvel is in the public domain (sort of).
Warning: It gets complicated. Do try to keep up.

Only the golden age Captain Marvel, as depicted in the comics that fell into public domain, (Specifically from his first appearance in WHIZ COMICS #2) is public domain. Non-public domain Golden Age appearances are under copyright of DC Comics, which owns the version of the character based on those comics and all subsequent versions published under DC comics banner.

Marvel Comics owns the trademark for the name Captain Marvel.
DC comics owns trademarks for the names "Shazam" and "Billy Batson".
In order to use Captain Marvel's name, it must be used in the interior of the story. The same way DC does to avoid Marvel's trademark on the name.

So if this in fact true, the version of Captain Marvel, as he is depicted in WHIZ Comics #2, can be used in new stories with the proper adjustments being made. (Specifically, a new name and alter-ego, and avoiding the word "Shazam", at least on the cover). Or... a new derivative character (with similarities to the WHIZ Comics#2 version) can be created.
As I've done here.

Best to stay clear of DC's copyright protect version.
Y' know, just in case.

It would help to have "The Wisdom of Solomon" to make sense of it all.