Given I’m currently getting my toes wet in this very topic (I’ve been a long time lurker, but I do have a BR campaign I’m toying with converting), I’ll post some of the stuff I’ve been experimenting with.
On Races:
Humans use the optional array, but with the following modifiers…
[ul]
[li]+1 to one characteristic relevant to cultural subset (Str = Vos, Dex = Brecht, Con = Rjurik, Int = Khanazi, Wis = Anuirean, and for the sake of completeness, Cha = Maesetian).[/li][li]+1 to any other characteristic of choice.[/li][li]Languages: native tongue + one other cultural human language of choice.[/li][li]One bonus skill proficiency picked from a short list as defined by culture (Anuirean - Deception, Insight or Investigation; Brecht - Acrobatics, Persuasion or Slight of Hand; Khanazi - Arcane, History or Mount [land]; Rjurik - Nature, Perception or Survival; Vos - Animal Handling, Athletics, or Intimidate; and again, for the sake of completeness, Maesetian - Medicine, Performance or Religion).[/li][li]One bonus feat of choice.[/li][/ul]
Elves use the Wood Elf subrace, Dwarves use the Mountain Dwarf subrace & Halflings use the Lightfoot subrace (I could see a good argument for tweaking the Halflings to get their shadow powers in, but I haven’t had the time/energy to do it myself. Always struck me as a tad overpowered anyway).
On Blooded Characters vs. Common Heroes
Commoners, instead of the xp boost, get an Inspiration boost (start with 1 each session, which resets with a short rest). Alternately just drop it as a rule option for Blooded characters.
On Classes:
Certain classes are restricted by Race, Culture or Background/Blood.
[ul]
[li]Barbarians restricted to Rjurik, Vos and some humanoids (Elves too maybe?).[/li][li]Dwarves and Halflings may not be Mages, while Humans may not take more than 4 levels unless they are Blooded.[/li][li]Elves may not be Clerics, Druids or Paladins. Dwarves may not be Druids.[/li][li]Monks - no. Well, maybe from freakish order from Aduria or some other far off place. The idea of Azrai Cultist Monks is kinda cool though.[/li][/ul]
At this point I’m sticking with the Domain & Bloodline rules as writ for 2e, editing how powers work in 5e as needed on a case by case basis. I’m really looking forward though to what other folks might come up with though.