A few possible candidates were Kyle Dubas (TOR), Brad Trelving (CAL former GM), Jeff Greenberg (CHI), and Ryan Martin (NYR). Which all seem to be out of the running, as Dubas looks to stay in Toronto, and the the Penguins have been rejected to even speak to the other three.
The Penguins are quickly running out of options, all though they have all summer to decide. Which is good and bad for the organization, the longer you wait the more the market may dry up. Meaning they might have to turn to in house. Taking the Flyers route, looking into former players or moving some people around in front office.