Yep stepping is B1.

Just set VTT to sweetspot of whatever bclk u run. So it looks like for that bclk u only need 1.18vtt, keep it as that. But to be honest i found keeping vtt closer to vcore helps stability. So if ur using 1.32vcore, then set a bclk/cpu multi combination in which it will NEED around 1.30vtt and 1.32vcore. But hey, it might not be the same on ur chip, or even the 875k altogether.