273 Compression Test Results

Think my manual says it should be around 120. I got a 67 273 HiPo that was rebuilt and
cam put in by someone, I only get around 110 on all cylinders. Think they put in 60 over
stock pistons instead of the HiPo ones and cam is too big. Compression is so low that I can't get it to ping with regular gas no matter how high I bump up the timing. Needless to say, engine is out right now and going to put in a stock 84 360 I got a year ago. Did a compression test on it and only get 120 in all cylinders.