several times when I've been searching ebay for old cameras (particularly attracted to whole-plate size) I came across several of those british-type half-plate cameras and the idea crossed my mind whether it would be possible to replace their old backs with some more modern ones to take fidelity-type 5x7 (or at least 4x5) film holders and thus get a simple "field" camera - to use on those days when the idea of lugging my Sinar is not very appealing..

Has anyone done this? What would I have to pay attention to, if I wanted to pursue that idea?