I would take either Grosso or Pasqual for the left-back position. But we all know that LYON doesn't sell a player unless they get paid a lot, so I think that we are more likely to sign Pasqual (too bad we haven't been connected with him).
Now about Zaccardo, yeah I wouldn't mind having him. I really haven't seen him play so I have nothing bad or good to say about him. But I would prefer Ivanovic since he can play as a CB or RB.
Zaccardo is the same as Ivanovic, in the respect that both can play RB and CB. The difference is Ivanovic is a better CB and Zaccardo is a better RB. I see RB as the greater concern, assuming some combination of Legrottaglie, Andrade and Chiellini are in form this season, and Chiellini and Criscito long term. Grygera is not starter quality for CL and neither is Zebina.
I actually thought Zaccardo looked better than Barzagli in the 3 or so Palermo games I've seen. However, Barzagli seems to have to cover for the defensive duties of his midfielders and lousy defenders like Biava... so maybe his Italy play is a better barometer of his skill in a better defensive system.
I would say Zaccardo would be an ideal summer signing assuming Birindelli retires and Zebina is sold. Right now, Grosso or Pasqual should be priority one. Not because Molinaro is bad, but cause Chiellini is so good at CB, and there's no credible cover at LB. Grosso in particular gives Juve a sure thing at LB with Molinaro there to cover as needed, and play in lesser games.
Personally, I would buy Grosso, Pasqual, or Barzagli now, loan Criscito, and negotiate for Zaccardo in June.