won't start after head gasket replacement?

[erikv11]

Did you consider this yet, from up above?

Does it crank over faster than normal (like the spark plugs are not installed)? If so, keep reading.
The tappets can expand while out of engine and hold valves open a bit. The compression will be low and it will not run and ends up wetting plugs. With plugs removed and ignition off, crank engine over two one minute periods. It will clean out fuel and the cycling of tappets is what is needed to get them to compress and let valves close.
Jumper starter at starter or use the jumper terminal that is a green red wire hanging out of harness just behind air filter housing.
Apply 12V to get starter to run.

Another guess is more classic "lawn mower syndrome," with same fast-crank symptom as above. You can try a teaspoon of oil in each cylinder and crank it a long time, until it fires and sputters to life. Many people have successfully fixed LMS that way.