Since there is no actual set equation to convert a race from one version to 5e, wouldn't it just be easier to use the same race stat bonuses and transfer it over?
For example, I want to have all the races from the 3.5 books in a 5e campaign. That's 63 races, including the "core" races. The only real difference is that I wouldn't keep DragonBorn as a core race, but return it back to the DragonBorn of Bahamut like it was introduced as. Is there a way to convert all these races to 5e and still have it feel like they fit?
Maybe things like the Dream Dwalf and Chaos Gnome would be Sub-Races?