Lucky dog. I'm a lucky dog.
I found an old Korona field camera on ebay. The camera is in nice shape but with a crumbly bellows. It just happens that the mp-4 bellows is the exact right size for the korona. It's too short to use the extension rail but will do nicely until a longer bellows comes along. Ain't I a lucky dog?
The next problem is finding a 4x5 back to fit. The Korona has a 3x4 back right now but was originally made for 4x5 I believe.