The first two of the actions on that  'Projects' post are still open [...], while the second required permission to reuse published material. This permission was granted recently: 'If you'd like to quote my zonal material, that's fine.'
That second action is a continuation of Zonal Qualifiers C01-C12 : Archive.org (June 2017), where I took 'the first steps for documenting the interzonal qualification process in C01-C12'. The numbering C01, C12, etc. is a convention I use to identify the different World Championship cycles that have taken place since 1948. According to that convention, we are in the 29th cycle or '2019-20 C29'. The complete cycles C01-C14 are documented on my page, Index of FIDE Events 1948-1990.
The table on the left shows my count of the number of players ('Plyrs') who participated in the interzonals for C01 through C16. The column 'Evts' (events) shows the number of interzonals that took place during the cycle. The column 'ZQP' (zonal qualifying paths) shows the number of players documented in the zonal material that I'm using as the base for this exercise.
The table gives me a guide for further work on this particular project. Ideally, 'Plyrs' should be equal to 'ZQP', although even when it is there might be a mismatch between the names of the players.
I've already documented the qualifying paths for C13 through C28, as shown at the bottom of the page Index of Zonals. The new data lets me complete C01-C12 and also lets me doublecheck C13-C16.