What's the highest CR you can safely run with pump gas?

I can't tell you for sure, but I can share this. I have a 440 RB with 11.5 to 1 and aluminum heads. The cranking pressure is 210 psi. I run 93 octane with Klotz KL-628 octane booster. I ran it with out the booster and got some rattle at throttle tip in and occasionally it would diesel when I shut it off. I used the 104 octane booster at first and it worked but it was pricey to run because I had to run a high concentration of it to get results. After researching octane boosters I found out that 104 and the other off the shelf boosters are too weak as sold. They only raise the octane by points and in .5 so your 93 become 93.5. The real racing boosters like Klotz raise it by whole numbers so it superior to the Walmart/parts store crap. I order the Klotz by the gallon off the web. Ts about $55 a gallon and I mix it 1 ounce to a gallon of gas so it adds about 40 cents to the cost of a gallon off fuel. It worked perfectly too, never pinged or dieseled at all.