Technically any story printed in 1951 would have been an Earth-2 Superman story, since the Silver Age is usually said to have begun around 1956 (with Showcase #4) or in Superman's case perhaps 1958 (with Action #241).
And none of my copies of comics from that era show Supes with gray hair.
Nor was he shown working for the Daily Star nor having a costume with a golden-age S logo on it.
I think the real guideline for whether or not the Earth-2 Superman should have grey temples in 1951 is his appearance in all those "Mr. and Mrs. Superman" stories. If I recall correctly, he had not yet gone grey.
Personally, I'm digging the Perez art in a big way. Though I agree the McGuinness cover is no great shakes.
Then perhaps you'll be pleased that the McGuinness cover introduces the Joe Kelly/Howie Chaykin/etc
Superman issue and not the Paul Levitz/George Perez
JSA issue.
I've read both the comics in question and my take on it is that although the Earth-2 Superman is back, he's a different character with a different continuity than the old E-2 Superman.
The
JSA story was fun. It read like an old issue of
All-Star only better and the artwork was fantastic.
I made another find while in the shop this week:
Alter Ego #56 was on the stands. It has some fantastic Superman material, including a Neal Adams cover and a never-before-published interview with Jerry, Joanne, and Laura Siegel from 1975.