Murlo you really need an ethanol tester haha. Tune to mid 11's on E70 and let'r buck at low 12's on real E85.
Edit: I forgot to mention, when I had fuel pressure issues on my V, it would go to 15:1 and never see knock, that was spring so it could have been less then E85. Granted it was only running 10psi but still, I wouldn't guarantee you have full E85.