It's not too bad if you have some patience. To get an iron head where I like it, I usually spend about 35 to 45 hours on it. Check out my website (
http://www.binaryweb.com) and look around for some pics of my ported heads. If I remember correctly, you can't go hardly any more than 0.450" lift on the stock valvetrain without having to have machine work done... high lift screws up the geometry.