Altering world height and min_y has no effect on world gen.

After hours of trying to get minecraft to generate a world using the full possible size capable of saving. Which would be:

height: 4064
min_y: -2032

logical_height: 4064

I had the idea of what would happen if I set the world sizes to:

height: 1280
min_y: 0

logical_height: 256

Upon loading into the world, everything looked like I had not modified any values like it had been for hours with the larger numbers. However when I flew down to y: 0 in spectator, I discovered that the bedrock had not even generated and the caves behaved like there was a world below 0. A few screenshots of y: 0 have been provided below.