If I recall, any Kz550 using Tk22 carbs use the same basic airbox with some variations for Canadian models.
There are several Ltd versions of the Kz550.
He can use an airbox from 1980-83 Kz550C1-C4. They used mechanical-slide TK22 carbs.
He can probably also use the airbox from 1980-82 Kz550A1-A3 (standard, but not the '83 A4).
He can probably also use the airbox from a 1981 Kz550D1 (Gpz).
There are also Canadian models with a slightly different airbox, but they would probably work too.
The shaft-drive Ltd models used larger, CV Tk26 carbs.
