Installing offenhauser intake

I have a 383 with a offenhauser 360 intake manifold that had a vacuum leak. So i removed the manifold and the valley pan and cleaned everything. My question is the valley pan extended up to the heads. Is this considered the intake gasket and if so do I need to apply sealer to one or both sides. What type of sealer should I use and should I use it around the entire metal gasket of the valley pan. I have done a lot of searching on the web and really cant find a answer to these questions.