Each system is designed for the particular machine. How the ZX-14 system can be "more efficient" than the 12R system is the combination of injectors, throttle bodies, ECU, camshafts and cylinder head. You would be better off and spend less time, money and headaches by tuning the 12R system to be efficient (better fuel economy?) by adding a professionally-tuned Dynojet Power Commander that can be set up for your desired parameters. Just slapping on ZX-14 fuel injection will not accomplish this. In fact, the effect may be opposite of what you believe.
You might also want to install a front sprocket with 1 more tooth than stock and possibly change the rear sprocket by 2 teeth. This will reduce acceleration but increase top speed and fuel economy without fiddling with the fuel system.
It may be a pig, but it's a pig with a rocket in it's ass!