In the Irish tradition, the shortie coats are encouraged. You do not wear a waistcoat or vest under it. With that point, you also DO wear a kilt belt and buckle, along with the sporran.

If I can figure-out where the pictures of this are located, I'll toss them on here later. It's worn for formal and informal occasions, and (with a tux shirt and bow tie) is worn at weddings. I've had to research this one extensively.

Thankfully I have GREAT sources! The buttons on the Irish jackets are NOT the square/diamond ones that you see in the Scot attire, but are round. Little differences to make the distinctions.

It looks like the options are out there, as long as you know the tradition that you're looking to follow.