I got the heightmap from chunkmapper, then I used Worldpainter to change the scale and raise the elevations so that the water matches Minecraft's default water elevation. Terrain and biomes were also edited with worldpainter. I also used a satellite image to help with leaving room for major high ways and cities.

I also added little houses with beds in them, they're scattered wherever cities and towns would be in real life.

You can also preview the map here:
https://www.minecraftworldmap.com/worlds/m4yCF/full#/2820/64/64/-8/0/0