FWIW, Larry- I agree with Doug. Head and intake manufacturers do the best they can on port sizes and orientation, using dyno runs and all when building their products. Then hot-rodders with die-grinders promptly alter the ports to match someone's stamped gaskets! Note also that gasket openings vary noticably from different sources. All I usually do is make sure the header flanges are flat, as welding distorts the finished product.