I would start by contacting these companies. They may have spare parts laying around or have a source for them. Daytona Parts helped me with a choke housing for my '56 Cad:
Carburetor Doctor Carburetor kits for all makes and models from 1927 to present
4107 - 50 St Rebuild services for all carbs
Alberta, Canada T7Z 1L5
780-968-6622 (country code 01)
Carburetor Rebuilders Co. Ltd.
4780 Fices Road
Toll Free (866) 990-8114
Tel: (416) 781-8114
Fax: (416) 781-3762http://www.carbrebuilders.com/contact.htm
The Carburetor Shop Carburetor rebuild kits for all makes, models, years
204 East 15th Street
Eldon, MO 65026
Daytona Parts Company Carburetor parts and total rebuilds. Helpful information over the phone to tune or fix your own as well.
Ask for Ron Hewitt or Tim Hewitt.