A couple names I would like to bring up that aren't discussed much are Jordan Hill and Nick Collison.
I know Hill is considered more of a combo power forward/center, but I watched him a fair bit last season and from what I saw I think he can develop into a fulltime center. Alot of teams in the league are moving towards quicker, aggressive centers with athleticism over the traditional 7 footers who simply use bulk in the paint. It started I believe back in the year Ike Diogu was drafted. I recall reading a Sports Illistrated issue that declared him the best "center" in college basketball and the college trend was towards smaller, quicker, yet strong centers. I think it came about because of the year when Kwame Brown, Tyson Chandler, and Eddy Curry were all taken out of highschool.
I read where college teams didn't put much emphasis on recruiting tall centers after that because they would just be drafted out of highschool because of their size so why waste the resources, so they began to concentrate on other players that could play the center role even if they weren't considered a true center. I think the NBA is catching on to that trend. Al Horford, Al Jefferson, and a number of power forwards have been turned into centers. Even Kevin Love in his rookie season, as well as using David Lee at times.
Getting back to my point, I believe that rather than forcing a lesser 7 footer into your lineup you might want to consider a different option. Jordan Hill, at 6'10", with a solid frame could become a Nene type player(and I don't mean the hair)

. Coming out of Arizona his comparison was Chris Bosh. He's actually stronger than Bosh. From what I've seen given the minutes he could be both an effective scorer and rebounder in the paint while still having a nice touch on his midrange jumper. He also got quite a few blocks in college and if his role was to be more of an inside presence I think he could get his share in the NBA as well. Houston didn't use him alot but if you study the games he got good minutes he produced accordingly. Also, with his age he would fit right into a quick rebuild with guys like Augustin and Henderson, and Thomas. And for some reason I don't think Houston really considers him a core piece so they might be open to a trade.
Nick Collison is that journeyman, blue collar type combo player that has been put into the center role. Smart, strong, and a work ethic that is rarely outmatched, he could be the steady, veteran presence for a couple of seasons while a young core was built up. I think given his fine play in this years playoffs OKC might value him more, but with Ibaka and Perkins maybe they would look at a deal.
So there's a couple other options to consider besides the mainstream thought of your classic 7 foot+ center. Just throwing it out there to think a little outside the box.