Save yourself the hassle of finding bits and pieces and helpful tips on the internet. You need to go out and buy an engine rebuilding/building book. There are numerous kinds out there for the chevy 350. Probably more than any other engine. When looking for a good one, leaf through the book. The valve train, pistons, intake, carb, etc should all be covered in depth with pictures. Also included should be specifications and clearances of various parts. Step-by-step books would be the best for a newbie.
That's my first suggestion - and a STRONG one at that.
Secondly, don't rush. The last thing you want is to fire up your engine only to find you have to tear it back apart because you forgot something/?.
Finally, have fun. I hope that someday soon I'll be able to go through the engine building process. I'd love to say that I built the engine in my truck from ground-up. (That may be a little while though /forums/images/graemlins/mad.gif)