Basically with the larger duration cams your effective compression stroke of the engine is reduced due to late intake valve closing. The guys are talking about dynamic compression when refering to low cylinder pressure. So what is done to compensate for this is you increase your static compression to make up for the lost stroke and lost low end power. I agree with the others with your compression and the duration on that cam you will suffer on bottom end power with your motor. You will never really make it up.
I would try to get at least 10:1 minimum with the cam you have.