Bruce,
Understood. The car this will eventually go into (maybe) is a V6 right now (don't laugh, it's all I could afford!). I spend some time over in a couple V6 forums as well. There's a large company out there called SuperSix that sells 'upgrade' packages for the 6-cyls. They swap heads, intakes, cams, all this crap, but it's rather poorly matched and ends up netting an extra 30-40hp. Then a fellow came along and just took a look at what would *match* well with the stock heads and intake, speced out some cams, and has people dynoing at +30hp at the wheels with JUST a $150 cam. Just goes to show you that one part chosen to match correctly is better than $1200 worth of parts that look good on paper.
Obviously I'm a beginner... I only really know two important facts about engine building. The first is that stuff has to match and work together. The second is to take whatever you *think* it's going to cost you, and triple it.
Fortunately I think those are the two most important things to keep in mind....