Calumet C1 parts?

Hello,
New here... I am a C1 user, purchased mine on Craigslist and refurbished (new bellows and glass and seeking out extra lens boards). I've not been able to find a couple nonessential parts, namely the rail's front locks and knobs. I'm also seeking a 5x7 reducing back (I only have 8x10 and 4x5 but curious about trying out 5x7). If anyone has any resource or leads on these parts?
Thank you!
Ian

On my former C1, I replaced parts like those with things I found at the local hardware store. The camera uses regular American threads, so the parts may have looked a little different, but they were functional.