I don't know the answers that you're looking for from first hand experience, but from the research and question asking I had done, 11.5:1 AFR was the most common answer I got to that question in regards to a street car. I know when Charley took the Mule on the Power Tour, he put a milder tune in it incase he came across some bad gas or some other unforseen issue, and it was in the high 10:1 AFR.
Oh, BTW, great avatar.
Cool story.