How about this... I did a search on Altavista for "shackleton avro". It came back with links to a group at RAF St Mawgans who are restoring the Shackleton at the gate and a link to a SAAF group who are restoring one as well. You migh try contacting one of those groups to see if they can point you in the direction of a set of plans....alternatively, you could try contacting British Aerospace(who bought out Hawker-Siddeley who had in turn bought out Avro?) and see if they have any info for you...
This might help too....
http://www.airpictorial.com/pages/ai...nsservice.html
Good luck
Edit:Add link