So you buy a zetec and fit bike carbs. OK.
How do you start it?
(Dont forget the ignition side needs sorting too.

)
You
could buy a set of GSXR carbs, send them to Bogg Brothers and get them setup for your engine spec and posted back attached to a manifold ready to bolt on.
You could then take Fords simple 'ECS' dizzy-less ignition system from an old MK3 fiesta or MK4 escort. Its 'plug and play' and will fit the sensors on the zetec. This can be found in your local scrappy for pennies.
Having done all this you'll be left with a thirsty out of tune engine that's not running to its full potential. The ignition map will be wrong and the carbs will use more fuel than an EFI system (granted they'll sound sexy).
Proper throttle bodies require custom management which = more expense!
My point in all this - keep it as Ford intended. Some Zetec-engined cars have a totally self-contained engine loom which makes it even easier. All you have to do is plug it in and live it up. Job done.