This cover-only appearance was among the last group of non-reprint Ditko releases from Charlton in the 1970s (with a handful more issues in Charlton's death-rattle in the mid-1980s). A decent effort, especially with the patterning on the curtains and the ghost/invisibility effect.
Plus of course some great hands. What is that weird pose with the two middle fingers tightly together and the other fingers spread out? I was just trying it, and it is not a pose that comes naturally to my fingers, at least, although it does look cool when Ditko draws it.