in this state of oxydation, Nevr-dullâ„¢ would take care of that.
To keep that shine, you have three opportunities (each with certain drawbacks):
- repeated polishing on a regular basis
- clear coat, either painted or powder-coated. Make sure the coating offers at least a temporary fuel resistance
- nickel or chrome plating the bowl. Platers in the US are not as picky when it comes to pot metal as Europeans, so you actually might find one who, at least, can plate the fuel bowl.