Need more of that pesky "technical info", but overall:
For 91 octane with iron heads and ANY advance curve, you're limited to about 9.0:1 unless you run a cam with a fair amount of overlap to bleed off cylinder pressure; downside to that is soggy throttle response.
Don't machine anything until you have pistons and some plan for the motor. You should have the heads measured to see what you have for chamber size.
You may well end up zero-decking your block, but that's not where a build, or a plan, starts.