Welcome to the addiction!! ATH, REB, DEF, and LP are all desirable traits in a center. Stamina also helps, obviously. Pay attention to Work Ethic as it will help define rate of growth.
Don't pay attention to the listed position though -- you are free to change that after your team shows up and can also play players out of position without penalty (assuming they have to ratings to play the position you want them to). So some of those PF's you have will almost assuredly be able to play at C for you as well (I literally consider PF and C to be synonymous when setting my lineups and just recruit "bigs" for my teams).
You might want to search the mentor list and see who is available to take on new players. Also, there's a player guide on here "How to succeed at D3/D2" that has valuable info. I'll see if I can find it and bump it for you so its on the first page. Again, welcome to the addiction!