[Loren]

Still trying to translate book,and relate to my swing,Came across hitters stickman,THAT made me understand Sooo much more in relation to c/face position on the plane,I still would like to know if there is preffered TOP of backstroke position (how far does b/swing extend)Thanks in advance

IMHO, FWIW, and all disclaimers regarding an unqualified opinion, there is no top "position".
It's wherever the backstroke ends, any length shot.
In my experience, for a full stroke, it's wherever left wrist cocking is complete in a right forearm takeaway, roughly shoulder high.

"This (TOP) section starts when the Backstroke motion of the Hands ends, and continues through a static period of alignment and relationship corrections, until a deliberate aiming of the Lag Pressure Point." (8-6)