Wow the car looks really good, great find.
Good advice there 39ClevoUte.
If it does turn out to be the sender the only realistic option nowadays is having it repaired. Its not cheap but going by the pics of the car would be well worth it.
There is another option. From what I've heard these fit and work with a little tweaking to the pickup pipe and float arm.
https://www.rarespares.net.au/raresp...-standard-tank
https://www.ebay.com/itm/31038735346...mis&media=COPY
Yours being a two litre it should have a second pipe for the fuel return line so these would need another pipe added to make them suitable.