dcapo,
Sorry not be more help here. Try the link below and contact Mike McCluskey or Pete. They use Butler's bumpers in their restorations.
I can't seem to get a number for him myself. My old receipts are gone.
At the very least, McCluskey will be able to get you lined up with what you are looking for.
http://www.mccluskeyltd.com/
Good luck! Making this contact will be well worth your time and effort. The parts are superb!
Al