You know, pencil neck could be Mirro.

The only pictures I've seen of him are from a decade later and he's a lot heavier. But he has the same jug ears and the goofy part in his hair.

I originally dismissed him from the group because I figured he was still in the slammer for the Zerk robbery, but he could have been out in '57.

Perhaps the light weight and goofy look were due to jailhouse pallor.