Yeah, I have that 45. I been trying to find out about these guys, I'm not 100% sure they are a blue-eyed group? The other 'Casinos' on 'Terry', Airtown' and 'Fraternity' are a white group from Cincinnati whilst as you say these are from Philly.
Great song but the photo is not them, this was a cover-up for a group called 'The Construction' (who are blue-eyed btw). The group pictured are the Del-Capris but they are an acapella group from New Jersey and had NO soul releases.
Here's the proper 45...
...and to confuse matters even more there was a soul group called 'The Del Capris' (no hyphen) who had a NS release on 'Ronjerdon' with a similar title 'Hey Little Girl' but I believe they were a black group.
I believe Fred Bridges is a black Detroiter, not sure about Bob Thomas though?
EDIT: https://soulfuldetroit.com/web12-fred-bridges/fred-bridges-text/03-fb-robert-bateman.htm