What's the general consensus about the best methods to clean/treat an old fuel tanks?

The tank from my WWII truck is actually pretty good. It appears to have been replaced at some point as the tank has part numbers stenciled on the bottom. Something that wouldn't have been done from the factory.
It only has some surface rust on the outside and very little on the inside since it appears to have a lead/tin coating.

Should I just rinse it with fresh gas and call it good, along with a clean and repaint of the outside?
I will need to source a new sending unit for the tank as it gives me about 45 ohms reading in any position.

You never know what you'll find in a gas tank....pulled out two rocks and a windshield wiper blade.