This is an average quality header gasket as sold by budget vendors.
Since we work on so many roadsters, we know that changing the header gasket is a pain and suggest using the best gasket you can buy!
We suggest these instead:
Premium Header Gasket U-20 | datsunrestoration (datsunrestorationproducts.com)
Low cost Header Gasket U20/2L
$25.00Price