That means pick the gaskets you want, measure them, and tell the shop to get the manifold flat and THEN remove the thickness of the gasket. If they just put the intake in the mill and remove the gasket thickness, it won’t be quite enough.
Don’t use end rail gaskets. Get some right stuff or similar and lay a bead on the china rails and go.
Edit: there is no such thing as a flat manifold surface. Not even on new manifolds.
