I have had good luck with Felpro header gaskets. They are the best you can get without going to copper header gaskets. If you are having problems keeping the bolts tight, try some allen wrench header bolts. It is easier to put them in. I have a combination of both 3/8" hex head bolts, and the allen wrench bolts on my headers, and i haven't touched a gasket in almost a year. Good luck!
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Lucas
"Another proud owner of one of the coolest trucks ever built"
drop_shift@hotmail.com
My Daily-Driver: '72 Chevy LWB Custom/10. Rebuilt 350, 300 HP thanks to a few go-fast goodies. Ochre with a white top. Future plans include a frame off restoration, and maybe a blown 383.