I've got a few lens boards I made by gluing (with aliphatic resin woodworking glue) two layers of Masonite/fiberboard, textured sides together, one reduced size to fit inside the standard opening and with an enlarged hole to clear the mounting nut. They could use a little felt added to tighten up the thickness fit on both my Anniversary Speed and my Graphic View, but they work fine.
The biggest lens I have on such a board is my 150 mm Componon in either Compur Rapid or Synchro Compur (don't recall which, and I'm not at home). This board, I'm pretty confident, would easily support much larger/heavier lens. As noted above, the original stamped aluminum boards will support pretty much anything you can mount on the board -- I've seen photos of them with huge 19th century barrel lenses.