From another project-gone-nowhere, here's a 5x7 bail back that I believe fits a Cambo. It's 8-1/2 square and for some reason has a Canham gridded groundglass, but it's absolutely not a Canham back (personally confirmed by Keith). The bail is a really nice feature that helps prevent camera movement when inserting or removing film holders. $135 to your US door? I'm happy to ship this internationally if you're willing to pay, contact me and we'll work it out.