12:1 is best rich torque in theory. But in reality you may need to compromise and run richer for ocatane/Knock sensitivity/high IAT's/high cylinder temps etc. I think that range is highly dependent on the setup.
Initial tuning and feeling things out perhaps start at 11.5 or even richer and see how it goes.
Thanks New2Tune for you reply , i am going to make some tests and logs to compare results , changing afr and timing a little.