That is not low compression. 80 is low compression. 3% difference between cylinders is very good.
A blown head gasked also dumps coolant to oil, causes bubbling in the coolant, along with very low compression.
If you torqued the bolts to spec, with oil or whatever lubricant the hardware called for, then it you start to overtighten them the material will start to yeild, resulting in a loss of clamp load.
Sorry to give you the business, it's just that I have NEVER heard anyone ask that question before. I figured anyone that could change their own head gasket would know the answer to this question. Sorry about that.
Go and enjoy your successful gasket change!!