Bob Powell - Unpublished? Splash Page?

Here's an odd item by one of my favorites, Bob Powell. The image is over 12 inches tall and still in a cheap frame with a typed letter (1977) from Jerry DeFuccio, who was gifting this to a friend. Unfortunately the letter is taped to the back of the art and the art is actually scotch-taped to the mat! For now I'll just leave it be lest I damage it in my attempt to preserve it. I have no idea if this was published, it has the look of an illustration that might have graced a sort of contents page, perhaps to a Street & Smith title? I would be very happy if anybody can further identify this for me. As usual, there is a lot of white out work here and the actual paper stock has tanned.