I was whining about my issues with the vest on Facebook with Claire Kennedy and she came up with the perfect solution for this vest. She suggested a waist dart. Slap me on the forehead! LOL. It's a great solution and doesn't destroy the lines of the garment while giving it a gentle shaping. Wow. I'm going to be so much happier with it now. You just establish your bustpoint and a couple of inches down draw in a dart stopping just shy of the seamline. Here are pics showing the change to the pattern and then the change in the muslin.
Side view of the dart.
Dart drawn out on muslin.
Tracing of the dart to my pattern piece.
Now I think I can happily move onto the embroidery!