Hi I’m from South Australia I have an 1961 s series that needs tlc

I just thought of something. I am not sure on the Aussie Valiants/Slants, but I think I read somewhere they used a different starter in the early years. You might want to check the number of teeth on the two different flywheels, and see if the number of teeth on the starter pinion, would be the same.
Maybe @slantsixdan can shed some more light on this.