I think with taking a few measurements of the correct spring, you have enough information there to create your own drawings.
Width of the material is 1.75" or 44.5 mm.
Thickness of 9 leaves is 1.75" so dividing by 9, one leaf the material thickness is 0.1945 or about 5 mm. They probably used 3/16", as they would have used some commercial standard rolled steel thickness. You can measure the thickness of the top leaf, and they should all be the same. The depth might include allowance for a bit of curvature, or they were lazy and just didn’t record the actual depth of 1-11/16", figuring nobody would ever make their own springs.
You can measure the length of each leaf from the center bolt to each end and add them.
Free camber on the rear means a measurement to the center of the top leaf from a bar laid across the leaf ends. It is a lot, which is why you need the special hook tool or a lot of strength to replace them.
Are your leaf ends rounded and tapered? Mine are on the Mark V and XK120, but on the '38 SS they are just cut off square.
If you get all that information prepared, the spring shop can order the material and get prepared in advance before you bring them your spring to match up.