What is the overall condition? Are there any loose rust particles inside? If so, I'd purchase a fuel tank sloshing compound from Eastwood or similar and coat/seal the inside.

I've used those products successfully on two tanks and they held up for over 20 years.

Do you have a radiator shop near you? The one near me also boils out fuel tanks and then seals them on the inside.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)