It could certainly be derived and cleaned to get it running well. The cost would be dependent on the state of the movement. There’s no way to restore the dial without trying to remove the lacquer (which has a good chance of a) ruining the dial, and b) it might not remove much of the mould) or simply repainting it, which will ruin the originality and cost money.
If you just want to cash out of it as you got it in a house clearance, simply sel as is. You won’t recoup the restoration costs when you sell.
If you’re thinking about keeping it to wear you can get it serviced and consider the options above. Personally, I wouldn’t get much joy out of it unless it had sentimental value so I’d just sell it and add some more cash to find a better one.
