Regarding the length of the bottom horns, I think you should just cast more of the yellow bottom horn for all of the lower horns. that one looks like a good length based on the game art.
These look amazing!
Are you still planning to sell some of them?
If so then I'd definatly be interested!
I think you may be right about this. So I tried it out in a test with all the yellow horns that I have. Here is the result on the right and for comparison the other horns on the left. Also I mounted the top horns rotated a bit so they look straight from ahead but have the devil curve to the back.