colour schemes

as far as I know it was just the following, and I'd happily be wrong

Black/gold  Interstate, Roadster, Hi Rider

Silver with black and red stripes on the tank (Interstate only)

Candy red with silver stripes , Interstate, Roadster

White with thick blue and thin red stripes  (Roadster only)

White - Interpol

I think in practical terms that you have listed them all, Sam...although the Spare Parts List also includes a black option for the Interpol both with radio pommel and recess...it lists a white Interstate too, but I suspect that was simply an Interplod without radio facilities.

It's very easy to swap...I have a set for my Mk3 in orange...but to be honest, on the Mk3 with its deeply padded seat and long black clock-holders with switch console, it doesn't look nearly as stylish as it does on a '72 750...I still like it, but even with early silencers and a 750 airbox, it's not quite right !

I have two Mk 3 bikes , one Interstate in Speed Triple orange and the Roadster in Harley Concorde purple (with silver stripes) 

I'm a proper luddite with tech stuff so I don't know how to do it. If you want to see the colour 

just look up images of Concorde purple Harley Davidson. It's a dark metallic purple (not metalflake) I love the colour, my Trident will soon be getting the same treatment

I can recall sat on my 1976 silver Mk3 Interstate in a local village pub when I heard “ Nice bike but wrong colour scheme “ 

My reply was that the silver with black and red striping was a classic Norton colour scheme, my comment was in question until a 1920’s Norton single pulled up next to me with a silver paint scheme and black and red stripping - I just smiled with great satisfaction!

This was back in 1979 (ish) - I sold that bike then had the pleasure of buying the exact same silver Interstate model (1977) in 2021. 
Happy Days!