Hi Mark,
Welcome to PF.
Back in 2016 I purchased some electrical wire (from Antics) to add some hair strands to my Nuts Planet '
Mother of Dragons'.
The wire comes in five very fine strands within the insulation. They can be used individually or twisted together for increased width.
Just click on the thumbnail for a larger view.
It's handy since, being wire, it can be bent to whatever shape you require.
The following is just a suggestion which may or may not be suitable to you.
Looking at your Native American I notice that the ends of the feathers appear to have some tufts at the ends from which the 'tails' protrude.
My approach to this would be to mix some epoxy putty and apply tiny balls to the feather ends.
Then, while still soft, I'd push one (or two) wire strands into it to create a hole. I wouldn't leave them in since I don't trust the putty to create a suitable bond.
Once the putty is hard, I'd firstly reinforce the feather ends with a dab of CA glue; after which, I'd fix the wires (with CA glue) into the ready made holes. When the glue is set, the wires could be bent to shape and cut as required.
I'd suggest a trial on some waste plastic or resin to look for any potential problems before attempting any work on the bust.
I've looked at the Antics website and found the wires I'm talking about
HERE (I wasn't aware that there were so many colours of insulation). The price has gone up by £1 from when I bought it; but that was 7 years ago.
Good luck with your project.
Cheers,
Andrew