Yes, the biggest difference between the ZX 14 and C-14 engines is going to be the bevel drive for the driveshaft. Everything else should fit / work in a C-14 frame, more or less. The ECU will also probably be a problem as it may not dovetail into KiPass but that one can be worked around I think by just removing KiPass entirely from the system.
If the bevel gear housing simply bolts onto an area already machined into a ZX, it should be quite doable and may even be easy. It might require a different output shaft though which may require the crankcase halves to be split. More likely Kawasaki changed the area where the bevel gear housing mounts and that is going to be the biggest difficulty I think. At that point, you are either going to need substantial machining and adaptation or will have to convert a C-14 over to a chain drive.
As someone already said, it is probably quite do- able to take all the engine internals that are different and swap the ZX parts into a C-14 engine. There will be a few things to deal with such as the variable valve timing hydraulic circuit but it should be relatively straightforward to simply block that off and you won't be using the sensors on that system anyway with the ZX 14 ECU.
I do have to say though that it probably is not worth it regarding cost and effort vs. final performance. You might be better off tweaking a C-14 engine, perhaps even with aftermarket ZX 14 parts such as pistons (assuming they fit the combustion chamber of a C-14 head) but still, lots of work and money for what I think are going to be marginal gains.
I think in the end it really would be easier to throw some custom body work onto a ZX, an automatic chain oiler for chain longevity, and add in an electric windshield than it would be to install a ZX 14 engine in a C-14 chassis.
Brian
I don't know the ZX14 motor but on the GPZ1000/GTR1000 the only difference was a bolt on bevel drive that connected to the shaft.
On the GPZ it was a straight drive with a sprocket for the chain and a chain/sprocket cover.
Could be the same for the ZX14/ZG14.
However, chances are the gearbox ratios will be different and there are bound to be other differences.
Whassup ZG,.... need a new project? 
