[hobgoblin351]

Like Thunder said, Always do the clay test! Even if they say the parts will match up check anyway. It's a easy thing to do and with the money you're spending you want to be sure you wont be throwing it away along with your motor.
Do you already have the 351W heads? You can go with one of the newer aluminum sets. They come with big valves and are set for screw in studs already. One thing about the cam though. If you're only going to go with .471 total lift(at the valve) why bother changing the heads? Yes it's probably a higher than stock lift but it wont take advantage of the bigger valve or port size. If you're going to the trouble of changing the heads so you can flow more air, flow more air! Dont let the cam be the restriction. You could probably run the cam with the heads that are on there and get similar results.