The Boston pickguard's holes line up with the holes on the original pickguard, but the shape is not quite right. The portion of the pickguard which touches the bass' neck is too tall, so when you install it, none of the holes line up with the holes in the body.
I am currently trying to sand down the section mentioned, but this is a tall order and is taking a mountain of effort to remove even a small amount of material.
My recommendation, just get a guard custom made instead. It'll cost more but at least it will fit and won't require reworking.