These will fit any horn (as far as I know) from 1958 or after. That includes 22H, 45, 47, 122, 142, 145, 147, 251, 760, 770, 

Print with the cone pointing straight up. Use a skirt instead of a brim. Add supports ONLY under the cutout, do not add supports anywhere else. These come out best when printed with 0.1 mm layer height.