That Soul Society arc was bootleg. You can't base power levels off that. Kenpachi defeats 2 captains with their bankai, and Ichigo beats him with a Shikai? That was just a point to be made. And then Ichigo needs a bankai to keep up with Byakuya and Getsuga Tenshou. It was typical only because Byakuya was set up as the main villain since he injured Ichigo and stole Rukia earlier.
Then Hollow Arc portrays Byakuya and Kenpachi as relatively equal and rivals. About right.
Then Byakuya has to be creative vs. that bookmark of end mother fucker and Kenpachi one shots the watch guy. Not a problem, still slightly equal.
Then Kenpachi beats 3 Sternritter and Byakuya gets owned. I'll attribute that to Kenpachi not relying on bankai, but I'd say if anyone had an upper leg it'd have been Kenpachi.
Now with this bootleg Squad Zero powerup I'll say they're equal again (only because Kenpachi's power is up, although if Kenpachi uses a bankai I'd say he'd be stronger than Byakuya).
So no, Byakuya wouldn't win.