Mine has WBH marked on the keys Weston body Hardware in the UK.
Link is here:
B20
But I have a very early car.
I'd contact Backdraft parts and ask who their vendor is. (Chances are since you have a late build# the vendor has not changed.)
Probably the simplest route would be to order a complete chrome latchset from Backdraft Parts.
https://www.backdraftparts.com/produ...-lock-set.html
They show out of stock but their sister website does show instock.
https://www.iconicparts.com/three-lock-set.html
Pull the snap ring off the base and cannibalize the lock tumbler sets for your Black Powdercoated handles. You'll end up with silver lock centers on the handles but they'll eventually get silver scratches in overtime anyways.