Sounds like a fun project! When you talk about the cameras you've seen with curved film planes, are you thinking of
swing-lens panoramic cameras such as a
Kodak Panoram or a
Widelux 1500? Or something with a fixed-lens and more standard format, such as the many simple MF cameras common in the 40's, 50's and '60's including the
Dead Link Removed,
Meteor, or
Agfa Clack? If the fixed lens type, I can probably think of many examples that might be useful as a reference for your design. Probably the biggest challenge with that type would be the lens itself, depending on just how wide you really mean.
Jeff