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 minimum recommended time you should run the blower to ventilate the bilge is four minutes. Before switching it on, however, rely on one of the most sensitive odor-detectors you have - your nose. No bilge blower will rid the compartment of spilled fuel, which will continue to emit vapors.