Unfortunately I'm not having luck finding Hyperman pics.
However, even though the GCD is down, if you know the code it's possible to pull cover pics. So here's a pic for Superman of 2965 (when this was reprinted in the early seventies the date was changed to 2465)--
The main difference is in the hair that swoops across his forehead (not easy to see from this profile shot) and a difference in the chin.
If I knew the code for Action Comics I could probably pull some other useful cover pics.
I said
I would use Christopher Reeve's likeness for Gregory Reed, because even though George Reeves was the inspiration originally, I feel Chris is more appropriate given overall continuity.
In his first appearance Greg was drawn by Swan and Anderson. And I've always felt the Swanderson version of Superman much resembles Christopher Reeve (by a stroke of sheer coincidence, since Reeve hadn't got the Superman part as yet in those days). So Swan and Anderson drew Greg (in full make-up) to look just like Supes.
Before the Superman movie came to the screen, when Chris was announced as the new Superman in Amazing World of DC Comics they made sure to point out the striking resemblance between Chris and the Swan Superman.
Later in the seventies, when Greg was used (he had been miraculously restored to full health so he now indeed resembled Superman) it was clear that the writers were intending him to be the Earth 1 version of Christopher Reeve (or at least an amalgam of both Reeves and Reeve).