Brake Help

I just bought this 77 KZ650 and the previous owner had removed the front brake entirely, well besides the disc.

I want to put one back on but Im not sure where to start. Will I have to buy each individual piece of the front brake system or can I find a complete unit? Can I use a brake system off another kz, like a 750, 1000 which parts are interchangeable or are there any at all? Sorry for all the questions, this is my first KZ!

Ask on this site, and the 650 info site if anyone has the parts.
Ebay could be a source too.
There are differences in the calipers over the years, as there are in the fork lowers, mainly where the mounting holes are located on the forks, which may affect the calipers too.

Find the post on how to use the Kawasaki parts diagrams.
There you can compare which models used the same parts.

Welcome.

thanks for the direction, was dreading piecing a system together!

it sucks buying a bike and having to correct what the other owners screw up. im going through the same problems on my 750. the old owner cut all kind of brackets off the frame and now im having to find ways to make it look original.