The aluminum foil will fit, I think. I will test it soon. It does not require holes when used on this keyboard because the foil seems to be flexible enough. (It only needs to flex by half a millimeter.)
There may be something about the fields from this keyboard (a Chicony KB-2971) that makes them easier to block. I have not had this much success with mice or other keyboards. I ordered the USB version (KU-2971) to see if it is the same.
The iron foil would require 1mm of plastic to be removed from the gussets on the back of the key plate (easy with sandpaper, a special knife or a file).