My head gasket blew at 235k miles. The overheating that resulted also cracked one of my heads. The job was not terribly difficult. There is a great series of videos on youtube that make the job much easier.

YouTube

I found a nice set of heads at a junk yard that I had resurfaced at a local machine shop. The gasket kit also included a valve cover gasket, so you can check that off your list as well. Don't forget to replace the head bolts, as they're torque to fail.

While the heads are off and all your valves are pulled out you can resurface them if you want to increase your compression. I resurfaced all of mine using Permatex valve grinding compound and saw an impressive increase in compression and power.