Here's some pretty handy information;
http://mountainbikers.hubsystems.com...s/chapter9.pdf
I might have an extra left crank around. Might not be an exact match.
How wide is your BB shell? If it's one of those Dutch GPs it might be a standard 68mm BB. My '70 Super Course happens to have a 70mm BB. There's plenty of Italian spindles that work for that.