Back to the centre discussion as per the OP:
Best will be an automatic selection, so you've got plenty of other guys competing for the other spot. My personal preference would be to play Bukuya there, since he's better defensively than anyone else we've got. I'd rotate him between back row and centre, and give all of the young guys a taste of FG. As discussed elsewhere pretty-much everyone we've got is a left-side centre, except maybe Mills. Pomeroy and Wright have shown that they can play a supporting role, but not as our first choice right centre.
Left centre:
1. Best
2. Pomeroy
3. Leutele/Wright
Right centre:
1. Sign someone (Inu?)
2. Bukuya
3. Mills