My original tumblr post was here. This image was researched by Bacchus at ErosBlog as part of the “Δ commission.” The research was originally published at Hedonix as Δ 034 One-Headed Space Hydra.” Here is what Bacchus found.

This artwork is cropped from the cover of Planet Comics #42 from May, 1946:

A gallery of additional Planet Comics covers is here. According to Wikipedia, all but three of the Planet Comics covers after issue #25 were drawn by Joe Doolin. It thus seems likely that Doolin was the cover artist for this issue #42. The ComicVine entry is in accord.