NRS, National Ropers Supply, does their custom bits in any width you want. I had a bit made for my fjordX that was great. Not super expensive either. Minimal trim and it was around $150 for an excellent bit.
I have a picture of it that I could post, too. I did sell the horse last year and the bit went with him.
do a google search for large western bits, or a specific bit and size that you want. Usually lots of options, and if you click on the "shopping" link, it comes up with all the different tack stores that sell bits in that type and size..