I will be using it as is or with tweaks guided by new features in new PHB.
Twilight cleric being the 1st to the "normalization" treatment.
Okay.
Personally, I think the options provided by the PHB should be plenty.
For the first post-2024 campaign, that is. Adding in lotsa-other-stuff can come later. It's much easier to get a feel for the new ruleset if you keep things clean. Also, the risk of inadvertently adding something unbalanced is much higher than most people realize.
Of course, you might be thinking of converting an existing campaign, in which case I do understand the desire to port across 2014 features.
However, I firmly believe player-side rules conversions are always a bad or at least mediocre idea. Much better to either keep using the campaign's existing rules and only shift once it's done, or to rebuild the content using the new rules.
Specifically, I mean "okay so you have a level N Twilight Cleric, let's keep using the 2014 ruleset until that guy's adventures are over" is the best solution. The next best approach would be "okay so you have a level N Twilight Cleric, now you get to build a brand new level N Cleric using only the 2024 PHB to use for future play sessions. If you manage to get across much or a little of the old character's look and feel, great! Otherwise, just give the new character a different name and don't pretend it's the same character, that also works!"
