The billet valley plates have a taper on the edges since they are designed to fit under an Indy head. When you use them with a standard head such as the Edelbrock or Trick Flow then you end up with a narrow gap between the knife edge and the head. You can fill in the gap with RTV but I think it will leak fairly quickly.

I can think of a couple of possible solutions but I'll have to make the parts myself to fix the issue since nobody else has solved the problem yet.