8 Speed Bar end- 9 Speed Cassette Compatibility

Hi,

I have just done a search and read the cassette compatibility sticky. I think I've answered my question but would a definate yay before swopping parts around.
I'm building an old skool steel time trial bike from bits I have laying about. Am I correct in thinking I can use an old 8 speed bar end shifter with a 9 speed mech/casssette providing that I only use it friction change and not indexed?
Or to put it another way, is the cable throw from inside to outside sprocket on cassettes more or less the same with 8 and 9 speeds and only the sprocket spacing changes?

Thanks