Intake manifold gasket installation help
Id not be hesitant to use a stock metal shim intake gasket on those iron heads. Thats how Ma M put them together 55 years ago. Composite gaskets on aluminum intakes. Those plastic set plugs mush to nothing when you torque the heads Crush almost like wax. Cork gets a bad rap because they always seem to leak under the valve covers where they either dont seal under a bent valve cover rail or get burned by headers. The cork at the ends on my 65 barn find intake were either original or replacements that had not leaked but most of that car was put away in 1976 and stayed that way until i bought in in 1996. Same went for my 90 oil adapters original (?) cork gasket and oil pan. it didnt leak at all! Those composite gaskets will cause the intake to sit higher as well as new thick head gaskets. Many times 273/318 gaskets start in 67 as the old poly 318 was still around until 67. Once upon a time they even made a 273 (only) head gasket...try finding one today.