Ostkurve,
(BTW what is your real name?), The headreast you show are the original ones.
The side holes are not for ventilation purposes but to reach the M6 Schluesselweite (s= pan width) 10 bolt which loosens & tightens the adjustment of the headrests with regard to their legs.
There are many later styles of these "ear-type headrests" around. However, only the 1968-1972 W108/W115 style is correct.
Later (from 04/1972 on to be exact) these were changed into a more rectangular shape of the W116/W107/late W115 which will work but are no longer original four our W113s.
If you hunt for a new interior set you need to make the shop (i.e. GAHH) clear that you have the original shaped headrests.
The hole itself is no problem since it can be cut/stamped in with a correct hollow punch.
Best,
Achim