I see many who know what they're talking about say that running hard with a not yet warmed up engine will blow head gaskets....
That's a good thread that Ker posted. It involves the TP rocker boxes, but it's good a step by step. I hope you have a manual and a torque wrench too. Raywood's advice on organization is good. Not a bad idea to take pictures and organize everything as you disassemble it. I use a magnetic bowl for nuts, bolts, and other parts--in fact I use several--one for the rocker box stuff, another for the tappet blocks, etc. Labeled sandwich bags are useful too.
I had a problem with the S&S rocker box bolts stripping when I followed torque specs, so I bought chrome ones 1/4" longer than stock. The extra thread contact helped.
You technically don't have to pull the jugs to replace the head gasket, but you'd be wise to do just that and replace the base gasket. Imagine how you'd feel if after all that work you had the gasket seep at the cylinder base. But you'll need a ring compression tool to re-install the pistons into the jugs.
There are those who insist that if you pull the front, you may as well do both cylinders and install new rings, hone the cylinders, and maybe deck the jugs and install a hotter cam..... But if your engine is good with low miles and the head gasket is the only problem, you can get away with replacing it.
Pay attention to torque specs and Loctite use..I like to clean threads with a wire wheel and clean internal threads with a bottom tap to make sure it goes together right. Here is a chart of most torque specs and what Loctite to use:
