I have wondered about this as well. I'm wondering if the heads were milled or something and the intake isn't seating properly. It did seem to sit on the engine fine when I dry fitted it. There was not much room between the China wall and the front of the intake. The supplied cork gasket would not have fit under the intake.
I cleaned everything very well, put some contact adhesive on the gaskets and stuck them to the heads. I also added a swipe of sealant around the cooling passages on the head and intake side of the gasket. Then a bead of clear sealant on the China walls.
