Yes the same would be true for the rear upper wishbone jig in fig 5.18
Looking at the drawing, if you are wanting to add the extra 10mm, you'll need a plate measuring 350mm X 257mm
The box section will be placed on top at one end, You'll then need to ensure that the 287mm measurement is increased to 297. This will set the wishbone 10mm longer.
I have just noticed that the ammended drawing in the annoncements section sows the upper rear wishbone length as 287mm
This is the same length as figure 5.18 in the first edition book !!??
To be honest, there is such a large amount of adjustment on the rear camber adjusters. 10mm either way shouldn't make a lot of difference.