I'd start with what you're trying to achieve is it more power, the look of ITBs or carbs the sound?
If say carbs is probably the easiest route but will fail emissions and probably poison the catalytic converter .
Motorcycle ITBs will need a standalone ecu, lots of wiring, custom manifolds, a tune etc.
There are ITBs that will suit the micra like jenvey but cost is big, they will still need standalone ecu etc.
There are easier and cheaper routes to more power on a 1 litre like cg13de cams, look to skim the head some to raise the compression, lightened flywheel . These do mean opening up the engine but ITBs will probably be a bit of a waste without doing these anyway.
The photo you have is ITBs not carbs, carbs don't have injectors.