I measured the top of the pattern piece with the pleats folded in (24cm Sz10) and made sure I made the top of the pattern this width. I used the curve of the top of the pattern piece with pleats folded to get the correct shape, I then used one of the portfolio dresses I have made and followed the curve down from under the under arm to the bottom. This made the template for the back.
For the front I decided to gather instead of pleat so made the pattern piece wider at the top but followed the same curve. I used the original front pattern piece for the top of the pattern and left the middle pleat unfolded to get the extra fabric for gather.
Top part of the Tunic made using more fabric from Ikea.
Left is the body made using the original pattern. Right is the body using new pieces.
I am going to try and finish my spotty Tunic tomorrow so will update with the results.