I could buy a seat post clamp that has a built-in cable stop, remove the inner lip and slide it all the way down to where the seat tube meets the top tube. It might look a bit agricultural, but could perhaps work?
In the end I decided against the cantilever brakes, I bought a cheap set of tektros and just couldn't set them up properly. So I got some XTR brifters and M560 LX v-brakes. I had these before and I knew that they are one of the best, most reliable and powerful v-brakes ever.
There is way too much red on the bike for my liking, but when you are on a budget you can't pass on a good part just because it is the wrong colour If I ever have the time I might re-paint the Z3`s. Or swap the frame for a gold Cinder Cone
The last addition will be a Hamax child seat and next spring we go exploring the local cycle paths with the little man