new heads on old block

I remember people saying that about Chev engines I think it's an old wives tell i've never had a problem, I'm assuming your gonna with 360 heads on a 318 for more power which doesn't work cause it drops a already low CR of a 318 to in the 7's for CR. What year is your 318 and is anything done to it now? Stock heads are not too bad good to about 325hp the weakest part about a 318 is the cam then Intake,exhaust and CR. Stock long block with a comp 262, headers and 650 4bbl made 282hp.