First of all, find out who this NPC is. It looks like someone who should have a name. Load the NCR Overhaul in GECK, go to Actors, then NPC, and search for him on the list. Then double click it, and in the first section that opens you can see which race he uses. Next, go to Actor Data/Race, and find the race, open it and mark playable. Save the mod, check your load order if everything is okay, because saving a plugin in GECK automatically places it to the bottom of the load order.
Back in the game check if you can set it as a race in your character creation menu, and if the end result looks okay.
If there are issues, we'll have to make a different approach.