I don't think Kourbelis is the answer in my opinion. I also like your line up and it is the most realistic one. I believe Fortounis is our best number 10 on his day. Pelkas can certainly compete with him. Are we ever going to see Mantalos play in his natural position? I'd really like to see Manthatis step up and grab a spot in the Olympiakos starting 11 and even be called up. I believe this might be Lazaros last season of great form as he is 33. Fetfatzidis can be in the team as now Skibbe has no choice but to recognize him.
To conclude, we need a number 8, someone who is capable of getting the job done in defence and attack. Bouchalakis has a chance to take it. I'd even put Fortounis there. Some one who can be just in front of Zeca (who should be the holding mid) to carry the ball and play along with the attacking midfielder to create opportunities for other attackers and themselves. But we won't see this as Skibbe wants to play and holding player there as we have seen in the past.