Stock steel covers in good condition, with good Moroso or Mopar steel-core rubber gaskets will work on almost anything. You're going to have trouble with any other type of cover on stock heads, because the gasket surfaces are nowhere near flat. Cast aluminum covers are nearly impossible to get to seal on stock heads because of this. The stiff aluminum won't bend to conform to the surface of the head. Cast aluminum or good stock covers will always work on aftermarket heads where the gasket surface is machined. I still like the steel-core Moroso or Mopar gaskets here.. You shouldn't need any sealer either. But as others have said, check to make sure those aluminum covers aren't getting hung up on the intake manifold. Some even hit on exhaust manifolds.