Cockroach Tarpon flies
There are 2 basic Cockroach patterns, the first was by John Emery, described by Lefty as a "Deceiver Style". The splayed grizzly feathers were attached about 1/2 way up the hook and then a collar of grey squirrel finished with a large black head ending at the ring eye.
The second was tied "Keys Style", by Chico Fernandez. He tied the feathers on just above the barb and had a black bear or brown bucktail collar with a black or brown head and left the hook shank bare.
The "Keys Style" is hard to define because Homer Rhode's flies of the 50's were called that but they looked like Seaducers and may or may not have been splayed?!?!
The Tarpon flies of today are a combination of the above plus different collar materials, eyes, flash, etc,.
Still, when you buy your feathers and start trying to get 3 or 4 long splayed feathers to lay flat against each other on the hook, then you will know why you bought the best you could find!
Books: Saltwater fly patterns- Lefty, Flies for Saltwater - Dick stewart, and Paul Schmookler's book Volume 2.