The white/black horsehair sporran the bottom of which is worn in line with the bottom of the kilt is essentially part of a piper's uniform and, as such, is inappropriate for wear without the rest of the piper's uniform.

Apart from any thing else, the wearing of a casual or otherwise 'civilian' kilt outfit with a piper's sporran looks incongruous, overdressed and, to be honest, ridiculous. I would not touch that combination with a proverbial bargepole, unless I wanted to be mocked by those in the know!!

Sometimes a bit of mixing-and-matching can work - but not in this case. Sorry!