What I did was found the cam for my goals then planned the compression around the cam to get to the dcr I desired. There are calculators and formulas to get you close. I have them written down somewhere. But take my advice and plan everything out and shop parts and all that before buying anything. Because I ended up buying stuff twice because I didn't plan ahead very well.
I'm looking at Howard's 255* / 261*. If I was to have a 9.42:1 compression ratio the dynamic is 6.43:1, is this a safe dynamic compression ratio for the cam I mentioned? No parts bought yet.