YOu have a great point there Dan. On that current build, I suggested to the customer that I do what I've done to a couple other LIM'*. Add material.
By adding the material and making your own gaskets, then using Permatex 26B, I have never had a vacuum leak or sealing issue of any type.
You may have to look close at the picture. The JB Weld blends into the color of the manifold pretty well.