There's only some slight surface rust on top of the welding seam;
And this despite the fact that the factory protection is rather flimsy to say the least, just one thin layer of paint without any primer. Although it is possible that the tank has been replaced somewhere in the past, as the area above the tank had some rather non factory rust protection. So only thing I had to do was remove the fuel gauge sender and fuel pipe, sand the tank down;
And with a few rattle cans of matt black paint, give it a new and hopefully better coating;
With the coating done I turned my attention to the fuel pipe and fuel gauge sender.
As the last one had been working properly before I dismantled the car I presume it still does. So only thing I did to it was give it a good clean.
And last but not least I inspected the inside of the tank before I put the fuel gauge sender and suction pipe back. Inside was rust free with no dirt worth mentioning, only what looked like chalk or crystal deposits. As this didn’t come of when I scraped it with a screw driver I didn’t waste any energy on it. This will also being taken care of by an inline filter!