1975 Z1B need help to verify

Hi I am new to the forum and am looking for some help I have come across a 1975 Z1B 900 bike I am looking at buying and need some help to make sense of it. The frame number is Z!F-75194 engine is Z1E-080735 but the bike is painted like a 1973 Z1 Root beer and Orange the engine is black I have attached the photo from the add. The person selling it is the daughter of the owner. What I am asking is how much is it worth?. And did they have this colour for a 1975 all the research that I have found is that this is a 1973 colour scheme only. I did not have my camera when looking at bike I can go back and take more pictures if needed. I am thinking value around 6500.00 what do you guys think. Engine has also just been rebuilt has about 500 miles on it and the pipes are period correct and are like brand new, the rotor is about the only piece besides the paint that may not be correct. your help is very much appreciated.

Handsome bike.

Looks like 1973 body parts (tank, side covers and duck tail) were put on the 1975 model.

Perhaps the engine was painted when rebuilt.

Good Fortune!

If carbs have top caps with three screws, they are 1976 or later carbs.

Good Fortune!

It's also possible that a 1973 cylinder block and valve cover were installed on the 1975 engine, perhaps incident to the rebuild.

Good Fortune!

The motorcycle is definitely a 1975 Z1B based on both engine and frame VINs. But it is cleverly disguised as a 1973 Z1...and some might find that appealing. I'm more of a purist. That aside, if you have transcribed the VIN's correctly, then the engine cases have likely been replaced somewhere in the life of the motorcycle. The trick in deciding if a Z1 has 'matching' engine/frame VIN, is that the two numbers are within 400 or less of each in other. The numbers you provided are several thousand apart. This would not have happened at the factory. So, this information is a strong negotiating point...$6500 is probably not a bad amount, bearing in mind that a Z1B with matching numbers would bring $10,000 or more and a real Z1 might bring $15,000 or more. You also might run all this by the fellows at www.Kawasaki-Z-Classik.com to get an even more opinionated view (some of the best Z-geeks on the planet live at that site).

Mcdroid wrote: ... The trick in deciding if a Z1 has 'matching' engine/frame VIN, is that the two numbers are within 400 or less of each in other....

Thanks, Mcdroid!

Thank-you for the info it is very much appreciated.