Deans is known to be a fan of McCabe's direct running, and tough NSW midfielder Rob Horne will be considered for a switch from outside centre to No.12 if the coach is trying to create a replica.
Some backline juggling could see Berrick Barnes or Adam Ashley-Cooper marking up against SBW, while inexperienced Queenslanders Ben Tapuai and Mike Harris remain in the frame.
With the opening Bledisloe Test in Sydney on August 18, McGahan confirmed a decision would have to be made soon.
"You want to be giving players the opportunity to train there and then be able to settle on that and give the whole team and the individual time ... and confidence," said McGahan from a training camp in Sydney on Thursday.
"Our primary focus will be how we want to play and how we want to defend. We'll look at the make-up of what they're going to come with, but it's what we want to deliver more so than what the opposition want to throw at us."
Quade Cooper will play club rugby this weekend for Souths in Brisbane, as he fights to get enough game-time under his belt to be considered for the No.10 jersey.
If Cooper gets the nod to start in Sydney, or if Kurtley Beale is brought from fullback into the frontline, Barnes could find himself back at No.12 where he played most of last year's World Cup as a secondary playmaker.
Ashley-Cooper is used to being the Wallabies Mr Fix It and says he'd be ready if required to defuse Williams.
"I approach any position the same - it's just a different number on your back ... we've got a lot of versatility in this backline which is great. Whoever steps up will do a great job," said Ashley-Cooper, who believes the Wallaby training camps have them on track to break their hoodoo against the All Blacks.
"It's hard to know if (Williams) will play 12 or 13 knowing Conrad Smith is out. Who knows if it's going to be Ma'a Nonu or SBW at 12?
"In itself, that's a challenge facing one of the best centres in the world."
Brumbies star McCabe says his stress fracture could be the result of a long season.
- AAP
