It is my understanding that only parts of the 1917 cannon that were abrogated are the issues that are modified or readdressed in the 83 cannon. Head coverings were not touched in the 83 cannon. So they are still required.
I could be completly wrong. I have never checked this out for myself, but this is what I have been told.
Quite wrong. Straight from the horse’s mouth, the 1983 Code of Canon Law itself:
"Can. 6
§1. When this Code takes force,
the following are abrogated:
1/ the Code of Canon Law promulgated in 1917;
2/ other universal or particular laws contrary to the prescripts of this Code unless other provision is expressly made for particular laws;
3/ any universal or particular penal laws whatsoever issued by the Apostolic See unless they are contained in this Code;
4/ other universal disciplinary laws regarding matter which this Code completely reorders.
§2. Insofar as they repeat former law, the canons of this Code must be assessed also in accord with canonical tradition."
So the entirety of the previous Code is abrogated. One of the exceptions to this entire abrogation needs to be proved in the case of headcoverings for them to stand:
"Can. 5
- Universal or particular customs presently in force which are contrary to the prescripts of these canons and are reprobated by the canons of this Code are absolutely suppressed and are not permitted to revive in the future.
Other contrary customs are also considered suppressed
unless the Code expressly provides otherwise or unless they are centenary or immemorial customs which can be tolerated if, in the judgment of the ordinary, they cannot be removed due to the circumstances of places and persons."
- Universal or particular customs beyond the law (praeter ius) which are in force until now are preserved."
Those are the exceptions - those are the things which aren’t abrogated.
Now headcovering has specifically been referred to by the church itself (I forget which document though, I’ll do a hunt for it later

) as a
non-normative discipline, so it doesn’t fit in as an ‘immemorial custom’ or a ‘universal or particular custom beyond the law’ what have you as per the above exceptions. Therefore it too is abrogated.