I did this for the first time recently on my truck and was also a little intimidated. In fact, this was the first time I even had to set timing on an engine so everything was new. To make it just a little more exciting, I drove the truck 300 miles to the in-law's house for the weekend and did the swap there. The only major problem I had was that the HEI was a tooth off when I finally got it back together. The truck started but sounded awful. I pulled the HEI back out, advanced it a tooth, and drove home the next day. It's not nearly as hard as it seems from reading all the how-to's.
That said, here's some more reading material:
http://www.oldengine.org/unfaq/hei.htm
http://www.pontiacstreetperformance....onversion.html
http://rmcavoy.freeshell.org/HEI.html