The Phantom Stranger story Horror in Miniature! was originally published in The Phantom Stranger #6, June-July 1953:
This story was reprinted twice by K.G. Murray. The first time was c. February 1965 in All Star Adventure Comic #31:
The second time it was published by K.G. Murray was c.December 1968 in Wonder Comic Monthly #44:
Note that it is in the second edition that the DC logo appears on the top of the pages as per the original publication.
In 1968 DC launched a new Phantom Stranger series. The first few issues carried reprints from the original 6-issue run but this was not one of them.
However, DC did reprint this story a few years later in House of Mystery #224, April-May 1974, and the story was retitled Mystery in Miniature!:
The retitling is accompanied by new host Cain introducing the story under the perview of the House of Mystery.
This version was published shortly afterwards by K.G. Murray in Super Adventure Comic #64:
Cain was excised for this printing. Along the right hand side you can clearly see the 1953 copyright for this story, which was also present in the House of Mystery #224 version.
I didn't know any of this when I first read this story, which was probably my first introduction to The Phantom Stranger. However it was not the story itself which made an impression on my 10-year-old imagination, but rather the cover of the issue it appeared in:
I reckon this cover is much bolder and more dramatic than the original cover to Justice League of America #103:
Of course, this is the DC instalment of the notorious Rutland Halloween Crossover, which again, I was not aware of as a kid, but appreciated the dissonance of the Marvel hero cameos in the DC Universe.