Well, the debate goes on...!
I have owned my car since 1985 (Australian delivered). The hoses fitted to the car when I bought it was the same as those you see on my car today. It is also the same material as the Air Intake Hoses to the cabin that run along the space under the Fenders (normally called the Catwalk) from the Front of the cars to the inside Air Vents. Would seem logical to me that Alfa Romeo would use the same materials.
The point is, today, this is what is available. For anyone who wants some Hoses, let me know. Others, please investigate alternatives at your leisure. Thank you.
By the way, in the Concours Handbook, these Hoses would be considered "disposables", like radiator hoses, tires, fan belts, brake pads, spark plugs, etc. and will not be judged against you for correctness, if you are not keen to take my quick investigations at face value!
Again, I have owned my car for almost 35 years. If anyone's ownership goes back longer than that, please speak up. I am happy to be corrected, but not on here say.