cylinder preshure and cam relation

i have a 340 that i put together with trw supposed to be 10.5-1 j heads and purple cam 268 .455 cam. i wasn't smart enough to measure how much the piston stuck up above the deck. cylinder preshure is only 150-155 psi.that seems pretty low to me. could it be cam related or is the cr realy that low. I did have to have the intake cut to lower it for port alignment with tells me the block wasent that tall. what would the cr actually bee with those numbers.another question i hear comp cams 268h mentioned a lot my moter doesn't have mutch low end would it be worth a change