Dedicated 318 header gasket

I can't seem to cure my exhaust leak at the 3,5 location. I have old Hooker Competition headers. I started with some white Mr. Gaskets and just bought some Percy's Aluminum but it still leaks. You can see the imprint on the header side goes into the gasket hole. These are for 318-360 size ports.Does anyone make a dedicated 318 sized gasket? I am thinking the smaller hole should help.