Replaced intake gasket, now my Malibu is misfiring

I have a 99 Malibu 3.1, spfi, M mortor, I believe. About a year ago my fiance replaced the upper intake gasket in my car and we have had no problems until about a month ago. I noticed that I was running low on coolant, I checked the oil and noticed my head gasket was blown. My fiancee ripped the car apart again and said no it wasn't the head gasket, it was the lower intake gasket. He replaced that and put the motor back together (changed the oil and coolant of course) and now the car idles at high (like a grand n a half) and is extremely bouncy and rough when put in gear. After test driving it I noticed it has no power and shifting hard (not a problem before hand). So my fiance does a compression test and notices the one cylinder he tested only had 60psi and I think it is suppossed to have 180psi. I know that possibilities are burnt exhaust valve, piston rings, cracked head, etc. But is the simplest a possibility too, where the head gasket was really blown after all?