As an option for the trailing arms have you had a look at bicycle pedal cranks, and using the long socket extension bars for the torsion bars?
In regard design, the Auto Union was a Porsche design as above.
I have yet to see it done that way Rhys, my issue with that idea, which was first mooted by the Giant Tribble in a design he produced as a concept, was the clearance for the turn of the wheels - bicycle cranks would not have given me much lock to interference without a lot of projection on the ball joints, which are probably the weak point of the design. I looked at torsion bar inclusion first, As that would have been authentic - I talked to Rick Eggers in the states as he has a great design but not transverse, in line, and he had to machine his socket extensions down to get the spring rate correct. - the MX5 bars are too stiff in their own right at 18mm (Although 5### series spring steel) - As the width of the CK limits the effective length of the torsion bar, including a link to another torsion bar seemed unnecessarily complicated/heavy/space consuming/inauthentic when rubber would do the trick (think Mini mk1?).
All very experimental Rhys at the moment and without trying I will never know if it will work. The plan is to get the front end welded up and braced first to test the deflection, bounce, rebound and the necessity for dampers before going ahead with the rest of the work. Things are busy here at the hacienda so it will probably be September before I know how well it performs.
JimR