I'm afraid the outcome does not change. Sasuke may gain lvl 3 tomoe, but he still lacks the lethal move set to kill Gaara.
Gaara goes in to his sand ball, transforms in to shukaku, and eventually beats Sasuke because his stamina runs out from Chidori.
If Sasuke is granted CM2 (I know you restricted it), Sasuke can easily take Gaara all the way to full transformed Shukaku, Shukaku then kills CM2 Sasuke with sand coffin.
Then again it was Naruto's taijutsu pushing Gaara to pull out 100% shukaku. 3 tomoe sasuke could probably push him that far. But 1 tail Shukaku will kill Sasuke, with or w/o Cm2.