Are you looking for something that threads into this
but has 11/16-24 Female threads, to mount onto muzzle threads?
Or, do you want the above to have 11/16-24 threads?
If you just want something that threads into the Xeno adapter, but with 11/16-24 female threads, buy a "Xeno Pistol Wee Brake", have a machinist drill and re-tap the threads, then cut-off the brake portion.
This should prove easier than having someone (especially a machinist) measure your adapter to make a part.