I would think the original coatee was a broadcloth wool, especially with all the military features on the coatee. Almost all military coats of the time were felted broadcloth. The way he painted the drape of the fabric suggests that it was a lighter cloth.

I also would not replecate the gold trimmed waistcoat in the painting, I think you could do better.

I agree with Robert that it could work as a daywear coatee or formal depending on what you wear with it if you have it made in green. The square buttons are used in formal wear now but they work so well with the coatee I would still use them.

details : are the epaulets buttoned on both sides?
the pocket flaps go to the bottom of the coat. Are they very short pockets or ornamental ?