I’ll throw in my two cent’s… could it be this? La tigre venuta dal fiume Kwai
Here’s a photo of the main character he looks “sort of” Native American (I know I’m reaching a little far here, but considering the circumstances lol).
I also found this site that looks like it has some info on the film. Scherpschutter has been on there (or possibly somebody is posing as him in the comments) He could possibly give you some insight onto the movie.
Wish I could help you out more, I’m actually going to look at some kung fu movies and see if I can’t find any leads.