I made a muslin for the coat. I made few minor alterations - took in back seams a bit, and narrowed the sleeves. I tried the muslin with original collar and with the mandarin collar, but liked more the first one.
Wrinkles on the back are a bit exaggerated by the camera. However, I think I will loosen those seams a bit.
Ladies, I have another question for you. I was thinking of the coat construction and quilting the lining. I wanted to sew by machine all the front/back panels of the shell and lining, and then sew the shoulder seams, apply the collar, and then quilt the lining to the shell. This way I would have to sew the lining seams by hand only on the sides. Do you think it would work?