Thanks, Yoc. I didn't know that you could search The Grand Comic Database by character. And, yeah, there are a ton of Red Masks. It seems to be a pretty common name in the Golden Age. I didn't spot my Red Mask in the search listing, but thank you for posting it.
twiztor, yeah, I figure he was probably created by Grant for the story, but my interest was piqued when I saw his name listed on the PDS entry. Also, Grant has used public domain Golden Age characters before in Zenith, so I figured it might be worth a look.