1924 Buick Touring backrest seat springs

[Rocketron]

Hi, I've purchased an unrestored Buick 24-45 that's mostly complete.  It's missing one backrest spring and the other backrest seems to be incorrect for the car.  The cushion springs seem to both be correct. 

 

I've owned a Ford model A for many years so I'm spoiled by the easy availability of parts for Fords.  But I'm new to Buick so I'm not sure what reproduction parts, if any, are available.  Can anyone tell me if they know of a source for reproduction seat springs for my car?

 

Assuming new is not an option, since I'm not looking to restore the car any time soon but I'd like to get it running and driving, I'd be happy to have someone's old rusty springs if they still have them and want to sell them.  And then I would also have a pattern for making something new when the time comes.