Can I use a cassette with an 11-tooth sprocket?

[The Hundredth Idiot]

Just checked and you're right - it's original Hyperglide rather than Hyperglide C.

I think, for now, I'll stick with the 12-28 which should fit on nicely. No point trying to run before I can walk with my first project - once I (start to) get the hang of it, perhaps the next one ...

 

[hamster]

The other option is to swap the freehub body to a later 7 speed one (say STX). I did that to the 1990 LX hubs on my Marin.