Well, it depends. If you want to run pump gas, then yea, you can't get away with much more than 10.5-11. If you plan on running $10 a gallon race gas, then you can get away with more, haha.
My buddy ran about 11.3:1 on pump gas without pinging. I've always heard you can get away with a bit more compression with aluminum heads because they draw heat out of the cylinders faster than iron. I wouldn't feel safe with anything much over 11:1 myself.
With a custom cam you could bleed some of the cylinder pressure off to make it work if you had to, although that defeats the purpose of having the compression