What a great topic! Volgens mij nederlands, but i will type in english for other users.
I came to your topic cause I had the same idea of using an aygo/1kr engine but then in a fiat 500. So I will follow your progression step by step!
I was wondering what do you think of the idea of turning the engine 180 degrees, so no need of cutting and turning the gearbox, with as a result that your driving shafts will turn the wrong side. To solve this I thought of using 2 volkswagen reduction boxes. This will also compensate for two other problems: the steep angle from gearbox to the wheels, and also the change in ratio of using the small diameter wheels of the fiat( using the reduction box the other way around).
A great topic and like to see more pictures coming! Btw I saw chiptunung of this engine resulting in 12 hp increase!