Well guess what..I decided to go full speed ahead and just do it -- and it's finished!!
The process was some learning curve, I tell you. The amount of redrafting I had to do in order to make it fit her was insane. But, as you can see, it ended up working out! The one big drawback is that because it's fitted closely at the waist there's no way it will fit her next year (I'm just hoping it lasts out the winter!). So I'll be making a new coat next year. I got a really nice wool melton for the body, lined it with a silk twill (in orange, Emily's pick!) and Emily picked out some vintage-y black buttons (she really wanted a vintage set I have but there weren't enough of them).
But what really makes this coat a success is that she loves it. She was asking to wear it the day it was done, and when she's worn it out she's kept it on every second.
This from the girl who last year would drop her coat magically right from her shoulders and take off in short sleeves because she "hates jackets" so much! And while it was a lot of work, I really enjoyed making it (and finishing it!). I even want to make a coat for myself now.
Lots more photos are on flickr if you want to see, and for more detailed sewing info you can check out the write up on Pattern Review.