Park Tool Repair Help & Education
WikiBooks Bicycles: Maintenance & Repair
http://blog.centurycycles.com/2009/07/techtalk-freewheels-vs-freehubs.html
http://forums.bicycletutor.com/thread-4492.html
http://trianglecycling.com/threads/possible-to-build-a-27-wheel-with-a-shimano-freehub.30802/
http://www.bikeforums.net/archive/index.php/t-609690.html
http://www.bikeforums.net/archive/index.php/t-803350.html
http://www.bikeforums.net/archive/index.php/t-719469.html
Shimano info: http://datenbanken.freepage.de/traut/SHIMANO.html
If you would like to use a nicer 27" rim than the CR-18 I would
recommend the Velocity synergy or dyad.