I had a '79 KZ-1000 LTD at one time. I'd say make sure everything is there
Carbs were almost an annual maintenance item for me, the points every two years. If the previous owner(s) installed electronic ignition, make sure it works. Rubber (and vinyl) bits should look in decent shape. This would include the airbox rubber bits, hoses, and brake lines. Am fairly certain the clutch is cable operated.
Chain sprockets should show no wear on the sides, and the valley profile should be parabolic. If it's a semi-circle toward the root, plan on replacing both sprockets AND the chain.
My two centavos,
Rick