didey,
If this was a 10,000 gallon, flat-bottomed (API-650 style)tank that was made from carbon steel, and shop fabricated.....I would replace it. If it was stainless, rework it
How old was it anyway ? Where is it ? Was the tank in some kind of corrosive service ?
The cost of straightening, rewelding pannels, painting etc a tank of this size is not worth it.
Replace it with a new properly coated and vented "shop fabbed" tank and consider it an investment
My thoughts only
MJC