Jimmm--I am pretty sure the GCD cover credit is in error. Most of these Dell adventure-strip reprints used covers drawn by house artists rather than (like Harvey did later on) using panel blow-ups or promo art. It's a nice drawing but those faces aren't Caniff faces.
This brings up a problem with the GCD. I'm hesitant to mention it because irate readers might accuse me of putting down the entire project. Quite the contrary. The GCD is an exceptional resource, the result of hard work by countless dedicated people. BUT.....art identification mixes research with large amounts of downright guesswork. The majority of art identifications are educated guesses by people with an eye for stylistic similarities. Some guesses turn out to be wrong, but unfortunately once an identification is posted in the GCD it tends to become gospel as sites like CB+ reference it.
In my own tiny area of semi-expertise, I've seen the GCD attribute to George Evans work by artists as diverse as Norman Nodel and Ed Robbins. In some cases it seems the attribution was made more because Evans was known to have worked on a series rather than by a close examination of the art itself.
Over the years the discovery of hard evidence, like Paul S. Newman's ledgers and the pile of Standard originals on which the artists' names were noted, has provided pockets of certainty. Hopefully more such material will surface. Even so, reversing mis-identifications may prove difficult now that the Internet has distributed them so widely.