Looking at my first edition of the book you are correct, two different lengths are stated !!??
Being as I worked form the drawings alone, I had not noticed this.
There is an ammendment for the first edition of the book this was to do with the lengths of the rear lower & upper wishbones.
The ammendment was to make the wishbones 10mm longer
I can only assume that the jig drawing is the pre-ammended length & the text is to the ammended length.
My own wishbones were made to the jig drawings + 10mm. They have all been test fitted to the chassis & running gear, all is fine.
If you do a search of the forum, you'll find a list of the book ammendments
Perhaps Chris will be along shortly to advise.
I hope this all make some sense.
EDIT
Found them
You'll find the ammended wishbone spec in this thread
http://www.haynes.co.uk/forums/showthread.php?t=2430