Skip down for tl;dr edition...
Basically I've got a map which I've been adding mods to as I've played (please reserve your judgment on the wisdom of such behaviour

Now, since the part of the map I've already explored conforms to my expectations (via Vanilla generator), regenerating would cause more pain than gain (I did give it a shot, and it had an unfortunate effect on my mining operations

Is there a method to modify the generator configuration for an existing save file? I've tinkered around with a few things like poking at game.player.surface and so on (read-only

Thanks for your time.