For what you are doing, the 30° seat is a waste of shop labor. And you wont get a 30° seat to run that great at high rpms becuase the valves tend to bounce. Least, that's what I'm told. 400hp is your goal. Have the heads done, stick 2.05" intakes in there so you're not worrying about seats, and you'll have just as much flow area from .000 to .050 as the 30° seat give you for a lot less money and I'll give anyone $100 if they take it for a ride and say it's sluggish from "too large a valve". Those heads with a hydraulic cam and real compression can make 400hp with no porting or mods at all. Least that's my opinon anyway.