Yep, looking at the engine number, it's a 1975 Z1B engine. I see it's got a Monty Campbell "X" Pipe fitted, I wonder why the owner took the Rickman exhaust off with only 11 miles on the odometer? It's also got KZ900/1000 idiot lights installed, while the "Rickman" speedo and tach are just standard Kawasaki gauges with Rickman faces. I see that Kaplan d1ck on Youtube video's all the time, and he's a bullsh1t artist, so I wouldn't believe too much of the blurb.
Nice bike though, there was a slightly rough Rickman CB750 for sale a week or two ago here in Oz for $15K (around $10K USD) that I thought seriously about buying, but was too frightened that the wife would find out.........