Edit: SOLVED!!!

Here's what I did (and yeah, here's me, modding on my birthday!)
I went into Object Window > Actor Data > Race.
Clicked on Caucasian > Edit. The Race panel pops open.
Single-left-clicked on Caucasian and selected Duplicate. This caused a "new" race to appear called CaucasianCOPY0000 to appear. Opened the new race.
Selected the Face Data tab. There's a drop-down called Default Hair Style. Changed this from HairDefaultA to NoukDreadlocks. (I made Dreadlocks.esp into an .esm beforehand).
Clicked OK. Then I found my NPC and changed his Race from Caucasian to CaucasianCOPY0000.
Went into the game. Voila. My G Zuss NPC looks like a cheap imitation of Jesus. ✝