Nice idea and may work, but only for a short time. the bottom end of these engines struggle to cope with the meagre revs put out by the standard set up. Even mild tuning is pushing it, so to hot the engine up further would require massive modifications in the crankcase to stop the crank splitting as well as overheating issues which would be very hard to control.
This is why you rarely ever hear of a 126 with a turbo, and rarer still you actually see one driving.