I use Felpro thick rubber gaskets and they last practically forever. big block: Federal Mogul 55288 or Pep Boys vs50145r. Hope this helps if you are still struggling.
I've been using these lately with good results....
http://www.autozone.com/external-en...t/felpro-valve-cover-gasket/72303_226226_6534
That's because back in the day, everyone traded in their cars every 2-3 years before they started leaking and falling apart.
I worked with another guy... He said it never had leaks because he used yellow Super Weatherstrip Adhesive on all his sealing surfases.
Yep, back in the day.......You also have to be aware of the age of cork gaskets. Old ones that have sat on a parts shelf for years will already be dry & brittle = instant leak
But it's a matching numbers car and has to be 100 point show car with NOS gaskets and all.You also have to be aware of the age of cork gaskets. Old ones that have sat on a parts shelf for years will already be dry & brittle = instant leak

For the record, I am not promoting gluing your engines together with weatherstrip adhesive. I was merely pointing out the ignorance of my young co-worker.
https://www.summitracing.com/parts/...-BC9sTK-BKEcZ5vnYQWTjkbrAzZgUIwjnYaAjX68P8HAQI bet they're hard to find now, but Chrysler used to sell exhaust manifold gaskets with built-in heat shields to alleviate this exact problem on late '70s New Yorkers/Newports/Cordobas with the upswept (like '60s "HP") manifolds. I used them on everything with iron manifolds until either Chrysler discontinued them or I left the dealership in 1994 (can't remember which). One piece laminated foil/fiber/foil gasket just like FelPro, etc. but with an extension to protect the valve cover area only.