The pattern I chose is this 1929 coat from Eva Dresss #33269 and I bought the larger of the 2 sizes that it's available in as it's easier to grade down a tiny bit than up a few sizes. And as we're used to a looser fit compared to back in the day, I may prefer this as is.
Clearly I'm not going to get it done in time for the competition, because only today I cut out the pattern pieces at lunchtime, and also bid for a not-too-vintage faux fur jacket to recycle as the collar & cuffs. I'm going to cut out a mockup in a couple of fabrics I kept for that purpose, and see if I need to do more than narrow the shoulders a little (if at all). That and shorten it as I'm more dwarf than elf.
I'm still going to use 4m of wine red wool fabric from the stash, and remembered some nile green silk crepe de chine that I'm hoping is enough for the lining. I may need to line the sleeves with something else.
(edited to fix the picture coding)