Buy it mate, $2K for a Z1/Z1A/Z1B is a bargain, regardless of condition. I started 2 Zed (Zee in the US) builds last year, but got sidetracked with a couple of Honda 750 builds, but I must get back to them, I have a 1975 Z1B like Steve's (same bodywork and color) but it is a hotrod Moriwaki 1100cc engine, with welded and indexed crank, ported head, Norris cams, underbucket shims, bigger valves, 33mm smoothbore carbs, Dyna 2000 ignition, Delkevic 4 into 1 etc.
I also have a 1977 Z1000 (KZ1000 in the US and Canada only, the rest of the world's bikes were designated Z1000, the German Concentration camps in WW2 were designated "KZ", so Kawasaki was a bit more politically correct for bikes sold in Europe especially) mine's a hotrod again, 1428cc Arias big block, welded and indexed crank, heavy duty everything, GPZ1100 head, 40mm flatslide carbs, Moriwaki exhaust, Brembo brakes, and repro Z1 bodywork, as it looks better than Z900/1000 plastics. I must get back to them and finish them this year, I keep forgetting I have them until I see threads like these and I'm reminded that I better get my arse into gear and get them going again.
They are great bikes, I had a 1976 Z900 back in the 80's and rode the wheels off it, and was blown away by the 80 BHP. Nowadays 80 BHP doesn't feel all that powerful when I have bikes with 140(+) BHP, but the Zed's (Zee's) were exciting bikes, back in the day, and they're still great fun to ride now. This is a pic of my Z1000 "Mad Max" bike before it morphed into a 1428, but the new big block engine hasn't made it back into the frame yet.
Regarding manuals, I managed to buy copies of the factory workshop manual and parts manual. If your bike is in bits, the parts manual is invaluable. If you buy it and have any "leftovers" let me know, I still need a few things.
Monday Zed meandering 24 Feb 2020 by
Terry Prendergast, on Flickr
Mad Max 28 Apr 2020 by
Terry Prendergast, on Flickr
1428 kick starter fix 18 Jul 2020 2 by
Terry Prendergast, on Flickr