Not a fan of Walton, but he is a young center who the coaches seemed to like. Blake is the only player I could see playing center outside picking up Koppen or another vet. Ramirez/Kuper are not centers, nor have they played the positions on a regular basis. It would be unreasonable imo to have either of them start.
Koppen is the best fit imo. Faine is interesting because he can pass protect pretty well, but other than both these guy, I see a lot of big power blocking guys.