A electric fan small enough to fit within the confines of the 126 engine bay, would not be able to provide enough ram air force to make a difference.
If you really wanted to make a difference, you *may* be better off running a piece of corrugated pipe from the engine bay up towards the front of the car positioned so it scoops air in as you drive. faster you go, the more air will be forced down the pipe into the carb.
There again, it may not even work to well with the distance it would travel due to turbulence created along the pipework.
If you *really* want to go crazy with power, shoehorn a Porsche lump in the back.. That would be mental!!!
:-)
Dave