One of these, a bizarre revenge story entitled “The Corpse Rides at Dawn” (Ten-Story Western, April 1948), was reprinted a few years ago in Damon Knight’s anthology Westerns of the 40s: Classics from the Great Pulps (Bobbs-Merrill, 1977).
A selection of MacDonald’s old and new science-fiction stories is available in his collection Other Times, Other Worlds (Gold Medal, 1978).
The ultimate word in MacDonaldology, giving full publication data on every scrap of his that has appeared in print anywhere, is Walter and Jean Shine’s A Bibliography of the Published Works of John D. MacDonald (Gainesville: Patrons of the University of Florida Libraries, 1980).