1. Sleeve Changes.
Gertie blogged about how to fix the sleeves slipping off your shoulders. I also shaved a 1/4" off the bodice seam and split the sleeves into two pieces. In addition to all of that about 3/8" was removed from the new center sleeve seam line to make the sleeves snugger around my arm.
To take care of the neckline gaping I made the following changes to the bodice pieces.
1. Left bodice piece
In the muslin I sewed a dart in the narrow end of the piece. To replicate this in the pattern, you'll need to slash and close that area as if there were a dart there. First step is to draw a dart the same size and location on the pattern as it was on the muslin. On my pattern it was about 2" and very close to the lower pattern notch.
Next cut one leg of the dart...
and close the dart thereby eliminating the extra length in the neckline.
This does make the curve of the neckline look a little rough, so add some paper to the top and bottom of the piece and smoothed the curve.
2. Right Bodice
One the right bodice I decided to remove the extra length at the inset seam. The first step to do this was to fold and pin the pleats on the pattern. Then on the seam line measure in the amount of length you need to remove and draw in a new seam line. On my pattern it was about 3/4".
Next you'll need to put the inset piece on top of the new seam line to make sure they are the same length. On my pattern they matched up fine. If they hadn't I probably would have made the inset a little taller to match the new bodice seam.
Since the seam lines match you can draw a new edge and trim off the excess.
The pattern edge will now look like this, which is fine because when you pleat and sew it the fabric will make a nice straight line.
3. Right Bodice Lining.
The right bodice lining is a little trickier since it's not obvious where to remove the excess neckline length. The best way to do this is to pin the pattern pieces together as they would be sewn. This is the right bodice, inset, and lining all pined together along the seam lines.
When you do this you'll see that the pattern pieces match everywhere except on the side seam. We'll take the excess length off here so they match up. Use the inset side seam to mark where the new lining side seam should end.
Then unpin everything and trim the lining piece. On my pattern it was again 3/4".
After making all these changes I mocked up some new sleeves and refit the dress.