I know a little about it. There is a data line that send the digital info to the Instrument cluster CPU from the ECU with exception to the fuel level gauge, oil level light and other indicator lights. If your aftermarket unit specifies it is compatible with the FZ6 you should be good.
I noticed that unit has a gear indicator. Where will that get it's input from?
Let us know if it works. I wouldn’t mind a more modern instrument cluster on my bike.
While this may work, it probably isn’t compatible with the Yamaha diagnostic codes. I would not modify the connector from the ECU to the instrument cluster. This way you can reinstall the OEM gauge for diagnostic purposes.