The meat doesn't just sloff off if you boil it.
You need to get a large kettle and some course nylon brushes from some place like home depot. From large down to toothbrush size.
Boil the head a little...take it out and brush the meat off. Then boil it again....brush the meat off.
You can blow the brains out with a water hose and high pressure nozzle.
Remove as much meat as possible prior to boiling. It stinks. It's best to do outside on a gas camping stove.
Be careful about over boiling or use chemicals like bleach. They can soften or eat into the bones.