KZ440LTD source for carb parts?

Hi,

My old 1981 KZ1981 is down and out and in the shop. It needs several
parts for the carbs. The service department is calling Kawasaki but I
know that if they are available the price will be absurd. Is there any
aftermarket alternative place to order or am I stuck hard here? The
vacuum slider thingies with the rubber gasket material are torn among
other things. I can't immediately see that it would make sense to try
to replace them from a cycle salvage place because old rubber is old
rubber and it might only get me up and running but not fix the problem
for long.

Thanks for any help here for sources for carb parts.

Winter