I recently purchased a 300mm Sironar-N for my 8x10 Burke & James commercial view camera. It came mounted on a Deardorff lens board, which has the same 6"x6" overall dimensions as a B&J lens board. However, the flange depth of a B&J lens board is 2.6mm and the Deardorff is 4.5mm. My solution to mount the lens on my camera? A trip to the hardware store for a stack of washers and slightly longer wood screws so I could shim out the sliding metal attachment things (what's the technical term?). Worked like a charm, and a lot easier and faster than manufacturing a new lens board from wood. The hard part was not dropping the tiny washers and screws.