An inch and a half seems like a huge amount to add between the waist and bust lines, but that's what I went with.
I also added a half inch along the bottom, figuring if the area above the waist needs lengthening the area below should be lengthened too. During the mock-up try-on I marked the waistline then transferred that line to the pattern. The pattern piece (second from right) that attaches to the center wraps around the waist at an angle, so the waistline does not run straight across the way I had originally measured. To get the correct waist measurement I took a bit out of all the pieces, except the back, through the center of each piece along the grainline. For reference, the waistline on the original pattern is roughly 26 inches.
Hopefully the second mock-up will fit better than the first.