I had a tank boiled out at a radiator shop and it never stopped making rust. It looked nice and clean through the sender hole but it continued to make enough rust to clog up a fuel filter.
Bought a brand new tank from a popular aftermarket supplier (made in Taiwan) and everything bolted up & works like the OEM it replaced.
Delivered to my door for around $150.
New tank, fuel lines, filter, cleaned out carb and zero fuel related issues.
Good luck
Dave