I have made a Wither Mob Statue at a 1 pixel : 2 blocks and a 1 pixel : 4 blocks scale. I usually build my mob statues at 1:2, but I need the 1:4 scale so that the Wither has the right size with respect to my other mob statues.
You can find schematics for LiteMatica and WorldEdit as well as a world save with both statues in the download.
Feel free to download and use them however you like, but please give credit if you do :)
Check out my Mob Statue Collection for more builds like this!