Unless your border fabrics are directional, it does not matter which way is up .... it could be turned either ways!
Although, I think you are also saying you are adding on more bargello strips before the borders, in which case, I think you need to take a look at how the design will play out, once you do .... add to the left? or right? or some on both sides?
I would never have thought of using a dotted fabric in a bargello, but I wanted you to know how much I like it! IN fact, I quite like the whole quilt!