I'm with Carl. If it's rubber go dry. If it's cork use a gasoline compatible gasket glue. Not silicone! You don't want that stuff plugging up your fuel system.
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'68 Parisienne 2+2 Convertible Matador Red (Resale Red but not for sale).
On the swather fuel tank sending units here at work they use a cork gasket. However, that's diesel fuel, not gasoline but for what it's worth, we do those dry too and it works well.
I suspect gas is tougher to seal than diesel though.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars