I spent 1.5 hours mowing my lawn so I had some time to think. :)
Assuming the above numbers are right what could it be?
-Leaky head gasket? Maybe he reused the old one? But its even accros the board...
-Maybe he never ground the valves? (can you loose that much compression from valves?
-Maybe...
Wouldn't it be too thick if the compression was dropping?
Thiner would raise the compression.
Maybe he just used he worng HG as you said.
You could always order the proper headgasket and replace it.
Maybe he put the wrong pistons in?
Do you have a recipt with what he did?
Cheers,
Nick