I gave up looking for a set for my 76 and built a set. Check with the Kawasaki win owners forum. They have some solutions for you like using a pair of boots for a 1000 and drilling out the holes to match up the mounting points(something like that). Other than that keep looking on ebay for a set and check carefully that they match you bike. Should go for 40-60 for the pair.
Not sure how much help this will be...
The diagrams at BabbittsOnline show that the Engine Intake Ducts are #16065-037. The diagrams there also show gaskets, but a note beside the part number at the bottom shows that the carb holder gaskets are used w #16065-030. The 76 Ducts are 16065-048.
You could get some measurements from the 76 ducts - bolt hole eye-to-eye & carb side ID.