So I've made a start. Of sorts. The plan is to build up a car around a new chassis and then transfer everything over to the original chassis if things ever get that far. I've created a chassis in CAD so I've got something to work with digitally. Setting up the suspension geometry is the first real priority and to get there I've had to work out the location of the various suspension pickup points.
Calculating the dimensions of each chassis tubes was relatively straightforward, as I've got my own chassis to work from and where it's been modified, there's no shortage of reference material. It's also possible to upload photos (to the internet) and use an online protractor to measure or 'gauge' angles. Or you can calibrate a standard printer to the dimension of a know part and print off the litem you need at 1:1 scale.
Just as an example. If you know the true dimensions of the top wishbone, you can print out a front view of the front suspension at 1:1 scale. Which means you can cut out a template of the mounting bracket. Or put the dimensions into CAD as I've done here. It's just a slow process.
To achieve a first pass I've also been using Allan Staniforth's Competition Car Suspension book and have started with the bottom wishbones as horizontal and the tops inclined at 15 degrees. Sharp eyes will notice that's not what the original Yimkins were running, Even sharper eye's - that period chassis photos include quite a bit of lens distortion.
Anyway; if you work backwards from the 'known knowns' of track width, ride hight and scuttle hight, along with the dimensions of the Standard 10 hubs and wishbones ... it's possible to zero in to quite a small area for each pick up point.
Next step ... adventures with a 3D Printer.
P.S. It can't really go unsaid. I used to own one of Alan Staniforth's cars and met him at Harewood Hillclimb when I was in my 20's and he was still racing. As mentioned elsewhere he was also acquainted with the Yimkin when my father was hill climbing it,