I am curiouse if the throttlebodies from a 2003 636 will fit a 2002 zx6r
I'm sure OP knows that and is looking to do an EFI conversion.Not likely!
The 2002 ZX-6R has carburetors. Not throttle bodies.
100% agree, one knows when a EFI conversion project begins but never knows when it will finish.....I have heard people who, having the injector body, believe that this is it, and they forget about the gasoline pump , ECU, atmospheric pressure sensors, intake vacuum, water temperature, intake air pressure, secondary injectors, wiring harness and the list goes on.....I'm sure OP knows that and is looking to do an EFI conversion.
OP, the two biggest questions are the diameter of the throttle bodies where they go into the intake boots and the bore spacing of the two engines, neither of which I can supply... You will also likely have to rework the airbox to something custom because it is extremely unlikely the throttle bodies will fit into the 2002 airbox.
Unless you're just doing this for fun it would be far more resource efficient to make sure your carbs are clean and working properly and the jetting is spot on for your set up and location.