why suspect the head gasket? The rings and faults in anything above them can be reason for compression leaks
Flatten the head surface with a piece of wet wet/dry 320 sandpaper on a flat piece of glass, water as lubricant, move it around evenly, like in figure 8's, till there's no low, shiny spots..
make a head gasket out of whatever is easy and available .. paper or whatever .. torque the head down to specifications.. do another compression test .. See what happens.
not that you'd prefer to, but headgaskets are so simple that you can make your own if you can find the proper material thickness and can cut it out.