Block test is also a good tool. In this case i would pressure test cooling system cold with system full keeping pressure on system for 15-20 minutes. Then disable fuel system and crank engine for 2-3 seconds without engine starting. Remove plugs and inspect for coolant on plugs. Should be a better test than compression test since coolant loss isn't substantial in a short period of time. I usually recommend changing both head gaskets regardless of which one is leaking. Good luck!