Welcome to another Canadian Maritimer:)
You have a few other Kz members that are in your neck of the woods and I am sure they will offer up some advice if needed.
The archives and search engine here on Kzrider are excellent and are often better than even the factory mechanic's manual as you are getting real-life advice from experienced wrenchers.
Z1 Enterprises is pretty much the preferred supplier of all things Kz here on kzrider. They can steer you in the right direction.
www.Z1enterprises.com
If you are looking for an obscure part that Z1 doesn't carrry then you might have to deal with your local Kawasaki dealership. If you are going to contact the dealership I would recommend going to the Kawasaki website and get the exact part numbers you need.
www.buykawasaki.com
You click on owner's info, motorcycles, the year and it will eventually get you to the parts diagram page. I find it helpful to cross reference bikes from the various years as many parts from the 1977 650 are interchangeable with models up in to the 80's. If the part is not available for the '77 you might get lucky with another year.
On the topic of carbs, the resident carb expert here on Kzrider.com is wiredgeorge. He has his own business rebuilding Mikuni and Keihn carbs for these old bikes. I have bought 2 sets from George and have been very satisfied.
If you are planning on re-doing the bike over the winter this would be a good time to get the carbs done by George as it often takes a couple of months given his work backlog. He will let you know approximatley how long it will take when you contact him.
I would suggest getting the carbs off the bike and taking a look before you send them to George as you might be able to deal with them yourself. But, if they need major surgery leave the job to the pros as you might spend a lot of time chasing down a carb issue that keeps you from reliable riding.
Keep us posted on your progress
Cheers-Colin Firth-Ontario Canada