If they are heavy wheels, it can have an adverse effect in the 1.2 8v as there isn't sufficient power in the car to drive them properly. You get all sorts of issues with wheel bearings and the gear box.
The 1.4 on the other hand has a stronger drivechain (inc. gearbox). So you'll be fine.
As for the size 17's fill the arches better and are cheaper to buy tyres for so I'd avoid 16's.
May I ask what is the best then
I assume 16's would be fine or lightweight 17's
Many thanks