I need some GOOD header gaskets

Well I finally got the pipes ran off the headers and damn the header leaks. I have some NOS CPPA 3/8 flange headers on some stock port J heads. I used some solid copper gaskets but they were real thin and couldn't conform to the flanges very well. Just for kicks I used a Mr Gasket standard gasket along with the thin copper gasket and that seals pretty well. But I know that is not a permanent fix. What do you the gang suggest I use for gaskets?