Never said that I would play them all at centre half, but I certainly wouldn't hesitate to play Barry Douglas, Phil Bardsley or Stephen Kingsley in defence. Tom Cairney and Stuart Armstrong should be considered for future squad selections, definitely involved for a friendly or 2 anyway.
You could actually make a decent squad with players that are not involved with Scotland
McDonald, Douglas, Anderson, Considine, Bardsley, Armstrong, Adam, Cairney, Shinnie, McCormack, Rhodes