Compression...

9.5 to 1 seems to be the standard.. but compression can vary on alot of things. Quench, and other variables effect it quite alot. When you have a really good quench, you can run higher compression, but if youre just trying to be safe in general, 9.5 to 1 is the standard Ive heard many times. Remember the 1 point discount for aluminum heads. Hope that helps.
Ryan