When you're intonating a low B string and you're at the saddle's farthest point away from the nut, and you're still sharp... Do you get a bigger string to compensate or a smaller one?
I cannot remember for the life of me
Smaller. Think of the Caparison HGS series with the bridges 4mm further away on a standard 648mm scale.
I've ust had two hours sleep though, so don't trust me.