Hey Nic-

do you have any idea what lens you want to use with the format? Since you're aiming for portraiture, that would push me to think you're not thinking "field" camera but rather something like a Sinar in a modern camera, or an older Agfa/Ansco or Burke & James for a classic camera. There are some older Agfas that take a 7" lensboard that will let you use some of the bigger barrel-only classic portrait lenses. If you're planning to shoot modern lenses in Copal shutters, then sticking to a modern monorail like the Sinar makes sense.