I have a build thread on a new vortec engine. I bought the cheap knock off intake and an edelbrock, the edelbrock has much larger ports below the carb. I believe its worth the extra money.
Pic of the openings in my vortec thread.
http://67-72chevytrucks.com/vboard/s...d.php?t=798068
I would stay away from the comp extreme stuff, just causes rumpy idle and carb problems, no real power gains....use something with a 112 lobe centerline. Howards cams has them, search Howards cam by part number on ebay and a guy is selling them for about $258 or so.