Cabriolet sub rails / cross sills

[1930.68B]

We are doing a restoration on a 1930 Cabriolet. We would like to make our own sub rails and cross sills but we don't have all the dimensions necessary to get the job done. The Cabriolet Club has drawings that show the shape of the wood parts but the drawings are missing some critical dimensions. Is there a reliable source somewhere get a complete set of dimensioned drawings for Cabriolet sub rails and cross sills?