"FordMuscle", here's a good article on head porting:
http://fordmuscle.com/archives/2000/...ng/index.shtml
I wouldn't say it was a waste of time at all. I agree that you can get Gt-40's cheap, but for the DIY types, it doesn't take much to get a ported set of stock heads flow even better. For a pure street car, why spend the big bucks!