For keeper, I would be shocked if either Marshall or Forster joined us as they'd both want assurances of first team football, something they won't get whilst Boruc is here. If they do join, then Boruc will probably go and we're in the same situation.
In defence, Kongolo might join us as Koeman was bringing him through at Feyenoord. Him along with Van Dijk from Celtic will probably be enough for the central positions (presuming Lovren goes). Personally I think if we're going to improve we need two new first choice centre-backs.
At left-back it depends on how ready Targett is and how much potential he has. If the club expects him to get to a good standard in future then we really only need an older player who can play for 1-2 seasons until Targett is ready, then provide some cover. If unlikely to make it, then a younger left-back would be a better choice.
Right back and Centre-mid are both fine in terms of quality and depth. If Schneiderlin goes, maybe put in a bid for Medel.
The three behind the striker (assuming that formation) we're signing Tadic, so him alongside Ramirez and Davies could be the three, with Rodriguez then coming back when fit. Victor Moses would be great and my first choice. Zaha is a definite no! A relative who's a Cardiff season ticket holder wasn't very impressed with him. I remember seeing him playing for Palace against us and Fox had him in his back pocket all game, leaving Zaha to throw a tantrum.
For striker, Pelle, Ings and Gallagher would be a decent front 3 to have. Depending on whether we go one or two up top, we might need another. This could be Mayuka or Osvaldo.