People have used the pan with and without gaskets and with and without sealer. (1) mockup & check that the intake/head interface angles are machined correct. (2) mockup the intake and valley pan & check the bolt hole/port height match. I use Permatex #1 on iron intakes and #2 on alum intakes, a thin wide swath around each of the 8 port holes in the metal valley pan on both sides. "superperformance" on here offers thin .015" fiber gaskets for reasonable money & Felpro has thick ones that come with the valley pan at your parts house.