Projects 1930-31 Sub-frame suggestions?

I have a 30-31 Fordor body I'd like to use, only it has no sub-frame. I'm told that the Fordor originally had one made of wood. I know that steel ones are available for all but the Fordor. Here's my question in 2 parts;

1. Does anyone know of a source for dimensions so I can fab my own from steel?

2. What size tubing would work best for this? (i.e. 2" x 3" x .083", etc)

Thank you!

 

Btt