Very hard to find in that length for what flies and uses is it for, TD , silverfox tail can be on length, if its for tails I use polar bear in that length
I use a lot of Cashmere Goat as a substitute for monkey hair. It is very long and very fine. Comes in many dyed colors also. For the build of tapered hair wings like I make on my flies I use Arctic Fox for the under wing materials and top with the goat hair and sometimes some peacock herls.Not sure it goes that long? As a plan b, have a look at Nayat or Kashmir goat, some fox is long, but probably not long enough, rarely over 4/4.5 inches
I have a large whole skin of an animal with long fine soft hair up to nearly nine inches long . Natural black and white hair possibly cashmere goat as someone mentioned.