That's Big Name Fan turned pro Dave Kaler on the right.
[Click on the image for a larger view.]
And before you ask, noI wasn't there to take this picture, though I wish I had been. I was only 12, and my first comic-book convention was still three years away. (As for Stan, I guess the goatee was still in his future.)
Though I've had the photo in a folder for decades, you'll have to thank either Andy or Pat Yanchus for its existence. One of them (they're not quite sure which; after all, it was 41 years ago) snapped it at this early con at the City Squire Hotel.