Paul there is no place in the US to buy plans. You can get the John Smith plans form
www.rollcutter.com Peter Hood is good to deal with. There are other Plans available of different designs from the Netherlands but some are only in Dutch which I cant read.
I do have plans for a Fair Organ its a Wurlitzer 105 which I am starting to make parts for now you can research it on the wurlitzer105b yahoo forum.
Hope this helps its a real fun project.
Jay