I can see two ways to repair this ultra rare tank:
1.) Braize all the holes shut. Hah...just melt the material and spread it over the top like butter
2.) Run a layer of fiberglass cloth or mat over the entire tank with a second layer over the seam. Great corrosion protection.
It seems to me that #2 is the best choice as when the tank totally disentigrates, I will have a more modern lightweight fiberglass tank.

Ok, if you are so inclined...let the opinions roll