Cam plays a part in the equation also. I run a Woods W6 with 10.5 to 1 and head work.
+1 on this. A cam with a lot of overlap will lower corrected compression ratio due to the lateness of the intake valve closing. Everyone rattles off mechanical compression ratios all the time, but corrected compression is a much more meaningful number relating to potential power output and also possible detonation with regards to the quality of the gas used.
what jetting is in your Mikini ? sounds like you need a bigger low speed. I had the
Se57 cam with 11:5 comp.w/42 mikini setup in my motor for 10 yrs. ran great.
doing a motor upgrade now.