I agree this is a really cool cover:
...but the story inside is so awful it kind of makes up for it.
And this one by Joe Kubert is also fabulous. The story is a bit off-beat, and not quite great, but as it deals with the still-in-progress war in Vietnam (an event so far as I know otherwise ignored in the super-books of the era), it certainly has some historical appeal...
But for the record, it wasn't Kubert's only Superman cover. He also did the cover...and interior art (YAY!!!!)... for this gorgeous issue of DCCP: