If you're really going to disregard Yujiro's earthquake feat, which I personally disagree with due to KT's arguments above, I'd suggest using this scale: Yujiro currently has an
accepted feat at 8-A caused by his presence alone.
As Hanayama implies the effect of endorphins on Baki
seems to at least double his power, and the Demon Back should give him an even bigger boost, so it would be fair to consider at least 4x for an endorphins + demon back boost
This would give Baki and Yujiro 953.6 Tons, which is still 8-A, but on a larger scale than before.