I feel like it's more like saying, we should build an airport here, because it's near a city and in a good location, and the land is cheap because no one else wants it for a number of reasons and this is the only thing that practically makes sense to go there.
It's not going to save a meaningful amount of money. But that doesn't mean it's a bad idea.
Sure. But even in your example the site selection won't help you much to build the airport, you still need to do that, and it's still going to be massively expensive.
I'm also in general skeptical about conversions of coal power plants into nuclear even for fission. Typical nuclear plants produce much milder steam temperatures and pressures than coal power plants, so their steam turbines are optimized for different conditions.
It's not going to save a meaningful amount of money. But that doesn't mean it's a bad idea.