There is no right or wrong place to position the spine. IMO too many guys writing these books don't understand what causes rod spine and that it has nothing to do with how the rod actually words out on the water.

Once you put guides on a rod and string a ling through it, all fly and spinning rods become stable no matter where you put the spine. The line always seeks the lowest point. No fly rod in the world is ever going to twist or spin on you when you're fighting a fish. The laws of physics prevent this from happening.

I'm happy to see that in later years now more and more of the world's better rod builders are discounting the spine [ONE of the rod building books points this out and shows why spine doesn't matter one single bit].

Sight down the blank and find the straighest plane you can see. Put your guides on this and wrap it up Go fishing. You'll love it!