According to Kawasaki, in the U.S., the KZ400 A1 is a 1977 model.
The 1976 models were S2 (special) and D3 (standard) models only.
In 1977 there was an A1 (deluxe), S3 (special), and a D4 (standard).
Before 1977 all carbs were piston type CV.
In 1977, the S and D got diaphragm type CV while the A got piston type CV.
In 1978, the B1 took over as the "Standard", and it had diaphragm CV. And the C1 took over as the "Special", and it also had diaphragm carbs. The A2 (deluxe) changed over to diaphragm CV carbs also.
The 1979 H1 (Ltd) along with B2 (standard), had diaphragm CV carbs.
So, it will depend on what year/model the engine is from to know what holders to get, and I'm not even sure which models use which size because Kawasaki.com seems to be inconsistent. There are apparently 3 part numbers:
16065-037
16065-048
16065-1002
I've made some holders for the piston carbs. Here are the dimensions I came up with.
It's for a 76 S2 and a 75 D2, according to Kawasaki.com.
I then attached the carbs with a section of heater hose. It's ugly, but worked great.