Pete,

Another thing that may help is using cork gaskets bonded to a steel core. It's a sandwich with cork as the bread and steel as the lunch meat. Cork is about as low tech as a gasket material can get but in my experience it great for sealing in oil at valve covers and intake manifold front and back ends. It does compress when first installed so a few retightenings are required. It was long ago but I think I remember Chevy switching from offset to parallel valve cover screws during the 1959 model year. If it's the parallel you have Fel-Pro #1649 is the "Steel Core Cork Lam" gasket set that fits.

Have fun!


Ray