Here is a thread that explains a lot more about the conversion just don't let it confuse you because it is very detailed about how the charging system works.
http://67-72chevytrucks.com/vboard/s...d.php?t=417872
One thing that makes a difference is whether you have the gauge dash or the idiot light dash.
If you have the gauge dash you have to wire the output wire to the stock location or the battery gauge will not work. the thread above explains it.