Found something! McCalls pattern M4745. It's a Civil War era costume pattern, and the Union officer has a long fitted double breasted coat. It'll be a simple matter of lengthening and straightening the lapels, shortening the jacket, opening the collar a bit for the jabot, and adding epaulets.
An uair a théid an gobhainn air bhathal 'se is feàrr a bhi réidh ris.
(When the smith gets wildly excited, 'tis best to agree with him.)
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