But then I hit a dead end. I have an archive of scans of a lot of older SF magazines, but not Isaac Asimov's. It had been scanned by Google, but was not available for view, as was one of the anthologies. I checked Open Library. Nothing. I checked Amazon. O'Donnell apparently hadn't republished it in an ebook. There were a couple of somewhat expensive copies of one of them if I wanted to wait a week or so.
I cast my eyes upward in annoyance, and they fell upon the anthology section of my bookshelves. The name Isaac Asimov caught my eye; I tilted my head sideways and read the much tinier print underneath it. Why, yes, it did read "Science Fiction Masterpieces" and that indeed was one of the collections that reprinted it.
And thus I am no longer annoyed, and have reread it as I wished.