For short periods of time, prescription medications (such as narcotic pain medications or muscle relaxants) may be helpful to alleviate pain or related complications.
It can take anywhere from 4-10 hrs. now if your head gasket is warped you will have to take it to have it milled that takes from 1 day to several days. if not you can just buy a completely new one that fits perfectly for about $150.
The main function of a head gasket is to hold engine compression while keeping oil and coolant circulation separate. Undetected blown head gaskets cause coolant and oil mixing, which could lead to severe engine damage, such as engine block cracking.