Stoich for E10 is closer to 14.1
The 360 mule I am testing with right now ,makes its best power and torque at 12.1-12.2 with 5 different carburetors I have been testing with. This is another non efficient combination though,8.8 to 1 compression aluminum heads,Comp Thumper cam.
How well the mixture is prepared can make a big difference. Part throttle tuning with different carburetors has been pretty revealing as far as rich/ lean conditions vs torque
Keith