Just to comment, I went on to read this,
http://www.sheldonbrown.com/free-k7.html which explained the difference between freewheel and cassettes. It looks like I can order the prebuilt wheels (although the web-page does not say what they are made of, I hope it is not steel) and put a freewheel gear cluster on it.
I may use my old one. However, if I get a new one, will a 7 speed work? It isn't indexed so I see no reason that it wouldn't. But, does anyone know if it wont?