I did the same thing for my first jacket.
It looks perfectly fine. Of course the worst thing about wearing a long jacket with a kilt is that it tends to hide the kilt somewhat, and a kilt is a thing of beauty that is meant to be seen!

However, it does look good on you.

I seem to recall that Hamish not only came across a kilt in a charity shop, but it was a perfect fit! How does he do it??