Edwardian frock coat -- The fitting fight

I've launched into the Edwardian frock coat, Laughing Moon Mercantile #109.  As you can see below, there's a lot of work to do.  Eeeeeek!

The size 40 vest fit perfectly so I cut the 40 coat.  Sadly, there's nothing "perfect" going on here.  The jacket fits fine in the front but is way too tight across the back.  The sleeves have also been problematic.  I thought while cutting them out that they looked big, and I was right.  The cuff ended up with a circumference of 14" which is larger than any winter coat I own.   There was also at least an extra inch of ease in the cap.  It was impossible to set the sleeve.   So far there has been so much to dislike about this pattern.  The shoulder seams extend to the back, so from the rear there is a hodgepodge of seams, none of which align with each other.  I'm not digging it. 

Before.....

After....

I let the center back seam out 1".  This has helped, but I still think I could add another 1/2".  It's hard to see but I've also narrowed the sleeve on the left.  I decreased the sleeve seams at the top of the sleeve by 1/4" , gradually increasing to 1/2" at the cuff.  This eliminated the excess ease, made the sleeve seam meet up with the curved back seam and made the cuff more suit like and less overcoat.  The sleeves will need to be shortened about an inch.  

Here is the front as designed.  It calls for 4 buttons down the front.  It's OK, but I have a fabulous vest that's completely covered up.  

I really don't care about historical accuracy, so my plan is to lower the roll line of the lapel so that some of the vest is revealed.  This might require narrowing the lapel and the collar slightly.  Both are easy fixes.  All in all this project is getting off to a rough start.  Making a muslin can be so frustrating, but obviously in this case it's been well worth it.  Next I need to tweak my patterns to match the changes I've made, and prep my fabric using the London shrink method.