Too much from the Pens, so I don't see that happening. Girardi would be awesome, however Stepan isn't really needed. I'm not sure where Staal for Girardi would value wise would be, and I'm not sure how that fits with the Rangers needs. ...
The only way I'd consider moving Letang is if it's a player like Weber coming back (with a long term contract).
Bold: would prefer you kick in a little more, but in one for one it could be a good match.
Underline: That's difficult to get. Think outside the box. Maybe Rangers add a little more to balance it out.
Unless someone like Staal was coming back for Letang I don't see how the Pens could justify moving Letang. And even then I'm not sure I'd really give that a lot of thought. The Rangers have a ton of young talented NHL d, but I'm not sure that's the answer, and isn't a step backwards. Letang is that good, and on a great contract.
Depending on what else the Rangers wanted added for Staal - Girardi, I'd even add slightly to that (say a 4th or a project prospect).
Girardi is on a great contract, has some size (6,1-206), eats minutes and can play a shutdown role.